7 p - 5 u = 15
3 p - 7 u = 33
Find the following values.
- 1 u
- 1 p
(b)
7 p - 5 u = 15 ---(1)
3 p - 7 u = 33 --- (2)
Make u the same.
(1) x 7
14 p - 35 u = 105 --- (3)
(2) x 5
15 p - 35 u = 165 --- (4)
(4) - (3)
15 p - 14 p = 165 - 105
1 p = 60
1 p = 60 ÷ 1 = 60
(a)
Substitute 1 p = 60 into (1).
7 p - 5 u = 15
7 x 60 - 5 u = 15
420 - 5 u = 15
420 - 15 = 5 u
5 u = 405
1 u = 405 ÷ 5 = 81
Answer(s): (a) 81; (b) 60