WAEC - Mathematics (2007 - No. 45)
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?
2
3
4
6
Explanation
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
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
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