6 V + 2 W = 38
7 V + 3 W = 47
Fill in the blanks.
- 1 V + 1 W = _____
- 1 V = _____
- 1 W = _____
(a)
6 V + 2 W = 38 --- (1)
7 V + 3 W = 47 --- (2)
(2) - (1)
(7 V + 3 W) - (6 V + 2 W) = 47 - 38
7 V - 6 V + 3 W - 2 W = 9
1 V + 1 W = 9 --- (3)
1 V + 1 W = 9
(b)
Make W the same.
LCM of 1 and 2 = 2
(3) x 2
2 V + 2 W = 18 --- (4)
(1) - (4)
(6 V + 2 W) - (2 V + 2 W) = 38 - 18
6 V - 2 V + 2 W - 2 W = 20
4 V = 20
1 V = 20 ÷ 4 = 5
(c)
Substitute 1 V = 5 into (3).
1 V + 1 W = 9
5 + 1 W = 9
1 W = 9 - 5 = 4
Answer(s): (a) 9; (b) 5; (c) 4