7 p - 4 u = 28
5 u - 8 p = 19
Find the following values.
- 1 u
- 1 p
(a)
7 p - 4 u = 28 --- (1)
5 u - 8 p = 19 --- (2)
Make p the same.
(1) x 8
56 p - 32 u = 224 --- (3)
(2) x 7
35 u - 56 p = 133 --- (4)
(4) + (3)
35 u - 32 u = 224 + 133
3 u = 357
1 u = 357 ÷ 3 = 119
(b)
Substitute 1 u = 119 into (1).
7 p - 4 u = 28
7 p - 4 x 119 = 28
7 p - 476 = 28
7 p = 28 + 476
7 p = 504
1 p = 504 ÷ 7 = 72
Answer(s): (a) 119; (b) 72