SOLUTION:

A NEW OG 2021 QUESTION

The question here tests on skills in __Unitary Methods.__

"c" is the FIXED Charge to be paid and hence PRESENT IN ALL OPTIONS.

Beyond "50" hrs, the x-50 hrs (as we know that x is beyond 50 and hence greater than 50) are the VARIABLE cost.

40 cents is the VARIABLE CHARGE per 30 min =>80 cents/$0.80 is the VARIABLE charge every hour

=> $0.8 (x-50) is the VARIABLE charge for the excess of (x-50) hours.

Hence total cost = Fixed +Variable charge for x hours

= c + 0.8(x-50) OPTION (D)

Hope this helps