A:b is

so 28:50 is

which is

which means it is 56% or .56
-(2/9)
=-{(1/9)+(1/9)}
=-{0.111...+0.111...}
=-0.222...
I added a screenshot with the complete question.
Answer:5 hours
Explanation:We are given that:
Revenue equation:
y = 420 + 72x
Overhead equation:
24x² + 180
We are asked to get the break-even point which is calculated by equating the revenue to the overhead cost.
This can be done as follows:
revenue = overhead cost
420 + 72x = 24x² + 180
24x² + 180 - 420 - 72x = 0
24x² - 72x -240 = 0
(x-5)(x+2) = 0
either: x-5=0 ..........> x = 5 hours (accepted value)
or: x+2=0 .......> x = -2 hours (rejected value as time cannot be negative)
Based on the above:
break-even occurs at 5 hours
Hope this helps :)