15:b=3:2

To solve this proportion, you can set up the equation:

15/b = 3/2

To find the value of b, you can cross-multiply and solve for b:

15 * 2 = 3 * b

30 = 3b

Divide both sides by 3:

30/3 = b

10 = b

So, the value of b is 10.