#### Otis

##### Senior Member

- Joined
- Apr 22, 2015

- Messages
- 1,643

Your work using the substitution method looks great. Some of your divisions were done in two steps (instead of one step), but you arrived at the correct values for A and B. (The exercise told you to use symbols x and y, but they're only names, so that's not a big deal.)

Your work using the elimination method looks good, too, until your last step. You had:

30A = 36

You tried to solve for A by subtracting 30 from each side. You need to

__divide__by 30 (instead of subtracting) because 30 and A are

__multiplied__together.

**IF**the left-hand side of the equation were 30 + A, instead, then you would subtract the 30.

Remember:

Subtraction undoes addition: (x + 5) Subtract 5, to get rid of it.

Addition undoes subtraction: (x - 2) Add 2, to get rid of it.

Division undoes multiplication: (7x) Divide by 7, to get rid of it.

Multiplication undoes division: (x/3) Multiply by 3, to get rid of it.

Good work! Cheers