7 H + 4 J = 47
8 H + 5 J = 55
Fill in the blanks.
- 1 H = _____
- 1 J = _____
- 3 H + 4 J = _____
(a)
7 H + 4 J = 47 --- (1)
8 H + 5 J = 55 --- (2)
Make J the same.
LCM of 4 and 5 = 20
(1) x 5
35 H + 20 J = 235 --- (3)
(2) x 4
32 H + 20 J = 220 --- (4)
(a)
(3) - (4)
(35 H + 20 J) - (32 H + 20 J) = 235 - 220
35 H - 32 H + 20 J - 20 J = 15
3 H = 15
1 H = 15 ÷ 3 = 5
(b)
Substitute H = 5 into (1).
7 H + 4 J = 47
7 x 5 + 4 J = 47
35 + 4 J = 47
4 J = 47 - 35 = 12
1 J = 12 ÷ 4 = 3
(c)
3 H + 4 J
= 3 x 5 + 4 x 3
= 15 + 12
= 27
Answer(s): (a) 5; (b) 3; (c) 27
