Suppose there are two goods with prices $ p₁ = 2, p₂ = 5, $ the income is $ M = 40 $ and the utility function is $ U (x₁, x₂) = (x₁)^⅓ . (x₂)^ ½, $ Find the optimum consumption plan.

Attempt:

I do not understand how to do this. The examples in my textbook are not explanatory enough. They are kinda complex. Can someone please help out with this question. The textbook says the final answer is $ MRS (x₁, x₂)= 2y/3x $

Its not an assignment question by the way. Just solving random questions.