Back to Student Worksheet
Math Grade 6-8 Answer Key

Solving and Graphing Inequalities

Use inverse operations and number lines to represent solution sets

Answer Key
Name:
Date:
Score: / 15

Solving and Graphing Inequalities

Use inverse operations and number lines to represent solution sets

Math - Grade 6-8

Instructions: Read each problem carefully. Solve each inequality and show your work. When graphing, use an open circle for < or > and a closed circle for ≤ or ≥.
  1. 1

    Solve the inequality: x + 7 < 15.

    Undo the addition by subtracting 7 from both sides.

    The solution is x < 8 because subtracting 7 from both sides gives x < 8.
  2. 2

    Solve the inequality: y - 4 ≥ 10.

    The solution is y ≥ 14 because adding 4 to both sides gives y ≥ 14.
  3. 3

    Solve the inequality: 3a ≤ 21.

    Divide both sides by the positive number 3.

    The solution is a ≤ 7 because dividing both sides by 3 gives a ≤ 7.
  4. 4

    Solve the inequality: n/5 > 6.

    The solution is n > 30 because multiplying both sides by 5 gives n > 30.
  5. 5

    Solve the inequality: -2m < 12.

    When you divide by a negative number, flip the inequality symbol.

    The solution is m > -6 because dividing both sides by -2 reverses the inequality symbol.
  6. 6

    Solve the inequality: -4p ≥ 20.

    The solution is p ≤ -5 because dividing both sides by -4 reverses the inequality symbol.
  7. 7

    Solve the inequality: 2x + 5 < 17.

    Use inverse operations in reverse order: subtract first, then divide.

    The solution is x < 6. Subtract 5 from both sides to get 2x < 12, then divide both sides by 2.
  8. 8

    Solve the inequality: 5k - 8 ≥ 27.

    The solution is k ≥ 7. Add 8 to both sides to get 5k ≥ 35, then divide both sides by 5.
  9. 9

    Solve the inequality: (r/3) + 2 ≤ 9.

    First isolate r/3, then undo the division by 3.

    The solution is r ≤ 21. Subtract 2 from both sides to get r/3 ≤ 7, then multiply both sides by 3.
  10. 10

    Solve the inequality: 18 - 3t > 6.

    The solution is t < 4. Subtract 18 from both sides to get -3t > -12, then divide by -3 and reverse the inequality symbol.
  11. 11

    Graph the solution x > 2 on a number line. Describe the circle and the direction of shading.

    A greater than symbol points to values larger than the boundary number.

    The graph has an open circle at 2 and shading to the right because x can be any number greater than 2, but not 2 itself.
  12. 12

    Graph the solution y ≤ -1 on a number line. Describe the circle and the direction of shading.

    The graph has a closed circle at -1 and shading to the left because y can be -1 or any number less than -1.
  13. 13

    Write an inequality for the graph described: closed circle at 4 with shading to the left.

    Closed circles match ≤ or ≥.

    The inequality is x ≤ 4 because the closed circle includes 4 and the shading left represents values less than 4.
  14. 14

    Write an inequality for the graph described: open circle at -3 with shading to the right.

    The inequality is x > -3 because the open circle does not include -3 and the shading right represents values greater than -3.
  15. 15

    A movie theater charges a $6 entry fee plus $3 per snack. Maya has at most $21 to spend. Write and solve an inequality to find how many snacks, s, she can buy.

    At most means less than or equal to the total amount.

    The inequality is 6 + 3s ≤ 21. Subtracting 6 gives 3s ≤ 15, and dividing by 3 gives s ≤ 5, so Maya can buy at most 5 snacks.
LivePhysics™.com Math - Grade 6-8 - Answer Key