Three types of bread flour, Q, R and S come in containers of 80 g, 160 g and 280 g respectively. Containers of Q, R and S are mixed together in the ratio 2 : 4 : 7 to obtain 16.56 kg of an assortment of bread flour.

1. How many containers of Q and R are used altogether?
2. Find the difference between the combined weight of all the bread flour in containers R and containers S as compared to the bread flour in containers Q. Express the weight in kilograms.

	Q	R	S
Number	2 u	4 u	7 u
Value	80	160	280
Total value	160 u	640 u	1960 u

(a)
Total mass of bread flour
= 160 u + 640 u + 1960 u
= 2760 u

2760 u = 16560

1 u = 16560 ÷ 2760 = 6

Total number of containers of Q and R used
= 2 u + 4 u
= 6 u
= 6 x 6
= 36 

(b)
Combined weight of all the bread flour in containers R and containers S
= 640 u + 1960 u
= 2600 u

Difference between the combined weight of all the bread flour in containers R and containers S as compared to the bread flour in containers Q
= 2600 u - 160 u
= 2440 u
= 2440 x 6
= 14640 g
= 14.64 kg 

Answer(s): (a) 36; (b) 14.64 kg