7 H + 4 J = 36
8 H + 5 J = 42
Fill in the blanks.
- 1 H = _____
- 1 J = _____
- 5 H + 2 J = _____
(a)
7 H + 4 J = 36 --- (1)
8 H + 5 J = 42 --- (2)
Make J the same.
LCM of 4 and 5 = 20
(1) x 5
35 H + 20 J = 180 --- (3)
(2) x 4
32 H + 20 J = 168 --- (4)
(a)
(3) - (4)
(35 H + 20 J) - (32 H + 20 J) = 180 - 168
35 H - 32 H + 20 J - 20 J = 12
3 H = 12
1 H = 12 ÷ 3 = 4
(b)
Substitute H = 4 into (1).
7 H + 4 J = 36
7 x 4 + 4 J = 36
28 + 4 J = 36
4 J = 36 - 28 = 8
1 J = 8 ÷ 4 = 2
(c)
5 H + 2 J
= 5 x 4 + 2 x 2
= 20 + 4
= 24
Answer(s): (a) 4; (b) 2; (c) 24
