When 15 is added to 7 times a certain number, the result is equal to subtracting 3 from 10 times that number. Find the number?

2 Answers
Feb 27, 2018

The number is 6.

Explanation:

Let's call the unknown number x and set up a system of equations:
7x + 15 = 10x - 3

Subtract 7x from both sides.
15 = 3x - 3

Add 3 to both sides.
18 = 3x

Divide 3 from both sides to isolate x.
6=x

Feb 28, 2018

x=6

Explanation:

Set up a system equation that satisfies the word problem:

overbrace"When 15 is added"^(15+) overbrace"to 7 times a certain number,"^(7x)

overbrace"the result is equal to subtracting 3 from 10 times that number."^(=10x-3)

15+7x=10x-3

Move all x terms to one side and all non-x terms to one side:

7x-10x=-3-15

Simplify:

-3x=-18

x=6larr"final answer"