5(3a 2b﹣ab 2)﹣4(﹣ab 2+3a 2b),
=15a 2b﹣5ab 2+4ab2﹣12a 2b
=3a 2b﹣ab 2
当a=﹣2,b=3时,原式=3×(﹣2) 2 × 3﹣(﹣2)×3 2=36+18