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
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
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
Source: Myschool Past Questions Archive (Record #36284)