Math: Expressions and Equations
Writing, simplifying, and solving algebraic statements
Math: Expressions and Equations
Writing, simplifying, and solving algebraic statements
Math - Grade 6-8
- 1
Write an algebraic expression for the phrase: 7 more than a number n.
The words more than tell you to add.
The algebraic expression is n + 7. The words 7 more than mean to add 7 to the number n. - 2
Write an algebraic expression for the phrase: 4 times the sum of x and 3.
The algebraic expression is 4(x + 3). First add x and 3, then multiply the result by 4. - 3
Simplify: 5a + 3a.
Like terms have the same variable part.
The simplified expression is 8a. You add the coefficients because both terms have the same variable a. - 4
Simplify: 12y - 5y + 2.
The simplified expression is 7y + 2. Combine the like terms 12y and -5y to get 7y, and keep the constant 2. - 5
Evaluate 3m + 4 when m = 6.
Replace the variable with the given number.
The value is 22. Substitute 6 for m to get 3(6) + 4 = 18 + 4 = 22. - 6
Evaluate 2x - 7 when x = 9.
The value is 11. Substitute 9 for x to get 2(9) - 7 = 18 - 7 = 11. - 7
Solve the equation: x + 8 = 15.
Use the opposite operation of addition.
The solution is x = 7. Subtract 8 from both sides of the equation to isolate x. - 8
Solve the equation: n - 6 = 13.
The solution is n = 19. Add 6 to both sides of the equation to isolate n. - 9
Solve the equation: 5p = 35.
Undo multiplication by dividing.
The solution is p = 7. Divide both sides of the equation by 5 to find the value of p. - 10
Solve the equation: k/4 = 9.
The solution is k = 36. Multiply both sides of the equation by 4 to isolate k. - 11
Solve the equation: 2x + 3 = 17.
Undo addition first, then undo multiplication.
The solution is x = 7. Subtract 3 from both sides to get 2x = 14, then divide both sides by 2. - 12
Solve the equation: 3y - 5 = 16.
The solution is y = 7. Add 5 to both sides to get 3y = 21, then divide both sides by 3. - 13
A school sells notebooks for n dollars each. Write an expression for the total cost of 6 notebooks.
Total cost equals number of items times cost per item.
The expression is 6n. Since each notebook costs n dollars, multiply n by 6 for 6 notebooks. - 14
A rectangle has length x and width 5. Write an expression for its perimeter.
The expression for the perimeter is 2x + 10. A rectangle has two lengths and two widths, so the perimeter is 2x + 2(5). - 15
The sum of a number and 12 is 20. Write and solve an equation.
The word sum means addition.
One correct equation is x + 12 = 20, and the solution is x = 8. Subtract 12 from both sides to solve the equation.