Answer:
A. x + 100x/y
Explanation:
Machine A= x hours longer to produce 660 widget than machine B
Machine B produces y% more widget per hour than machine A
let
b = Number of hours it takes Machine B to make 660 widgets.
Time taken for Machine A to make the 660 widgets = x + b.
Rate of Machine B = 660/b
Rate of Machine A = 660 / (x + b).
Machine B produces y% more widgets per hour than Machine A:
660 / (x + b)(1 + y/100) = 660/b
1 / (x + b)(1 + y/100) = 1 / b
Multiply both sides by (x+b)
1 + y/100 = (x + b)/b
1 + y/100 = x/b + 1
Subtract 1 from both sides
y/100 = x/b
Take the inverse of both sides
100/y = b/x
Make b the subject
100x/y = b
b=100x/y
The time taken for Machine A to make the 660 widgets is x + b = x + 100x/y.
Answer is A. x + 100x/y