Explanation

A + B = 15 ... (1)

A - B = 3 ... (2)

Adding (1) and (2), we get:

2A = 18

A = 9

Substituting A into (1), we get:

9 + B = 15

B = 6

Now that we have the values of A and B, we can find the value of AB:

AB = 9 × 6 = 54

Finally, we can find the value of 4AB:

4AB = 4 × 54 = 216