Two whole numbers A and B satisfy the following conditions. Find A and B.

A+B=30
A:B is equivalent to 2:3.

since A/B = 2/3, A = 2/3 B

now add them up
2/3 B + B = 30
5/3 B = 30
B = 30 * 2/5 = 18
So A = 12