book Maths Puzzle Numerical Ability

Please help, have I done this correctly? I have nothing to compare it to.
Problem: (X^3/5 Y^-2)^5(2X^-4/5 Y^3)^3
Work: (X^3 Y^-10)(8X^-12 Y^9) = (X^3/y^10)(Y^9/8X^12) = X^3Y^9/8

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