6 W + 4 X = 76
7 W + 5 X = 91
Fill in the blanks.
- 1 W = _____
- 1 X = _____
- 3 W + 3 X = _____
(a)
6 W + 4 X = 76 --- (1)
7 W + 5 X = 91 --- (2)
Make X the same.
LCM of 4 and 5 = 20
(1) x 5
30 W + 20 X = 380 --- (3)
(2) x 4
28 W + 20 X = 364 --- (4)
(a)
(3) - (4)
(30 W + 20 X) - (28 W + 20 X) = 380 - 364
30 W - 28 W + 20 X - 20 X = 16
2 W = 16
1 W = 16 ÷ 2 = 8
(b)
Substitute W = 8 into (1).
6 W + 4 X = 76
6 x 8 + 4 X = 76
48 + 4 X = 76
4 X = 76 - 48 = 28
1 X = 28 ÷ 4 = 7
(c)
3 W + 3 X
= 3 x 8 + 3 x 7
= 24 + 21
= 45
Answer(s): (a) 8; (b) 7; (c) 45