26> budget constraint is : 50x +10y =750
by solving optimisation problem, u will get x=3 , however he is given 250 as book grant so he has to purchase 5 books(x) and spend all of his income on movies.
So, optimum: x=5 and y=750/10= 75
27> budget constraint is: 50x +10y =1000 +10y
=> 40x + 10y=1000
(since, he gets one movie free on each book he purchase)
Now, solve like all other problems,
u will get x=5 and y=80
:)