The total mass of 3 packets of black bean and 9 bags of red bean was 45 kg. Each bag of red bean was 7 kg lighter than each packet of black bean.
- What was the mass of 1 packet of black bean?
- What was the mass of 1 bag of red bean?
(a)
Mass of a bag of red bean = 1 u
Mass of a packet of black bean = 1 u + 7
3 x (1 u + 7) + 9 x 1 u = 45
3 u + 21 + 9 u = 45
3 u + 9 u = 45 - 21
12 u = 24
1 u = 24 ÷ 12 = 2
Mass of 1 packet of black bean
= 2 + 7
= 9 kg
(b)
Mass of 1 bag of red bean = 1 u = 2 kg
Answer(s): (a) 9 kg; (b) 2 kg