book Maths Puzzle Numerical Ability

Hello-
This one I made myself, though I can't seam to find one formula to cover it. I have the answers, but if you could give me the formula, i'd appreciate it!

James owns 8 d

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book Other Question

4/3r - 3 < r + 2/3 - 1/3r Please detail how solution was achieved?

Simplify and evaluate:
(x3y-4z0/5x6y8)3

Thank you in advance.