Answer: 45b^4/32
Step-by-step explanation: First multiply the two fractions
15b^3y(3b)/8y x 4
Multiply 3 by 15
45b^3yb/8y x 4
Raise b to power of 1
45(b^1b^3)y/8y x 4
Use power rule to combine exponents
45b^1+3 y/8y x 4
Simplify
45b^4y/32y
Cancel common factor of y
45b^4/32
