hi there, was hoping you could show me how you would go about answering this question. I've had a go and answered it but was wondering if there was an easier way to do so?

Madam Lim's sister, Angela, has the following utility function U(x, y) = min(x, y}. The prices of Kopi (x) and Kuih (y) are $3 and $5, respectively, What is the minimum expenditure that allows Angela to attain the utility U - 77