7th Grade Math

Solve a Subtraction Equation

Solve x - 2 = 1. Check your solution.

x - 2 = 1 Write the equation.

+ 2 = + 2 Addition Property of Equality

x = 3 Simplify.

The solution is 3. Check 3 - 2 = 1 ✓

Solve each equation. Check your solution.

e. y - 3 = 4 f. r - 4 = - 2 g. q - 8 = - 9

SHOPPING A pair of shoes costs $25. This is $14 less than the cost

of a pair of jeans. Find the cost of the jeans.

Words

Variable

Equation

Shoes are $14 less than jeans.

Let j represent the cost of jeans.

25 = j - 14

25 = j - 14 Write the equation.

+ 14 = + 14 Addition Property of Equality

39 = j Simplify.

The jeans cost $39.

h. ANIMALS The average lifespan of a tiger is 17 years. This is

3 years less than the average lifespan of a lion. Write and solve

an equation to find the average lifespan of a lion.

210 Equations and Inequalities

Addition Property of Equality

Words If you add the same number to each side of an equation,

the two sides remain equal.

Symbols If a = b, then a + c = b + c.

Examples Numbers Algebra

5 = 5 x - 2 = 4

+ 3 = + 3 + 2 = + 2

8 = 8 x = 6

Models A bar diagram

can be used to represent

this situation.

jeans, j

$25 $14

shoes

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