Question

When 4 times the number increased by 30, the answer is the same as when 70 decreased by the number. What was my number?

Answer 1

8

Explanation:

Read a little bit at a time.

• 4x + 30 is the first clause
• 70 - x is the second clause. These two things are equal

Equation

• 4x + 30 = 70 - x Subtract 30 from both sides

Solution

• 4x + 30 - 30 = 70 - 30 - x Collect like terms
• 4x = 40 - x Add x to both sides
• 4x + x = 40 Combine
• 5x = 40 Divide by 5
• 5x/5 = 40/5
• x = 8

Answer 2

x=8

Explanation:

4x+30 =70-x

Add x to each side

4x+x+30 =70-x+x

4x+x +30 =70

5x +30 = 70

Subtract 30 from each side

5x +30 -30 =70-30

5x = 40

Divide each side by 5

5x/5 = 40/5

x = 8