Henri's utility function is min{x, 5y + 2z}. The price of x is 1, the price of y is 15, and the
price of z is 7. Henri's income is 44. How many units of x does Henri demand?
(a) 9.78
(b) 11
(c) 5
(d) 3
(e) None of the above.
答案为什么是b啊？？