A messenger was paid N2.50 an hour during the normal working hours and 4.00 n hour during overtime. If he received N31.00 for 10 hours work, how many hours are for overtime?

A.

2

B.

3

C.

4

D.

6

Correct answer is C

Let normal working hour = x

let overtime = y

after 10 hours = N31.00

1 x 2.50x + 4y = 31

4 x x + y = 10

2.50x + 4y = 31
- 4x + 4y = 30
----------------
-1.5x = -9

x = 6; x + y = 10

6 + y = 10

y = 10 - 4

y = 4hrs for over time