Answer:
y ≤ 8
Step-by-step explanation:
given equation,
5 y + 16 ≤ 56........................(1)
to solve the equation (1)
subtract both side by 16
5 y + 16 - 16 ≤ 56 - 16
5 y ≤ 40
dividing both the side by 5
hence,on solving equation we get y ≤ 8
discount=MP-SP
=Rs420-Rs405
=Rs15
the radii would equal 7.5