Solve `y = 7(15 + x)` for x.

Divide both sides by 7.

`y/7 = (7(15+x))/7`

`y/7 = 15 + x`

Now subtract 15 from each side.

`y/7 - 15 = 15-15 + x`

`y/7 - 15 = x`

**The solution is x = `y/7 - 15.`**

Apply the Golden Rule of Algebra: "What is done to one side must be done to the other side.

Divide both sides by 7.

`y/7=15+x`

Subtract 15 from both sides

`y/7-15=x`

Apply the symmetric property of equality.

`x=y/7-15`