Question 387118
A=(4B)        (A)-B=9

On this one substitution is the best way to go. You can plug in 4B from the first one into the second one, replacing the A.

(4B)-B=9 Simplify
3B=9 Divide by 3
B=3

Next, plug that value for B into one of the original equations to solve for A.

A=4(B)
A=4(3)
A=12

Your answer is (12,3)

This is the point that these two lines will cross.