What values should A and B have so that the next system of equations has an infinite amount of solutions?

Ax - 7y = - 18

8x - By = - 9A

for the system to have an infinite amount of solutions, the equations must be equal

Ax - 7y = - 18

8x - By = - 9A

a/8 = - 7/-b = - 18/-9a

a/8 = 7/b = 2/a

using cross products

a^2 = 16

a = 4

then

4/8 = 7/b

4b = 56

b = 56/4 = 14