Three types of bread flour, W, X and Y come in containers of 120 g, 180 g and 210 g respectively. Containers of W, X and Y are mixed together in the ratio 2 : 5 : 7 to obtain 23.49 kg of an assortment of bread flour.

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

	W	X	Y
Number	2 u	5 u	7 u
Value	120	180	210
Total value	240 u	900 u	1470 u

(a)
Total mass of bread flour
= 240 u + 900 u + 1470 u
= 2610 u

2610 u = 23490

1 u = 23490 ÷ 2610 = 9

Total number of containers of W and X used
= 2 u + 5 u
= 7 u
= 7 x 9
= 63 

(b)
Combined weight of all the bread flour in containers X and containers Y
= 900 u + 1470 u
= 2370 u

Difference between the combined weight of all the bread flour in containers X and containers Y as compared to the bread flour in containers W
= 2370 u - 240 u
= 2130 u
= 2130 x 9
= 19170 g
= 19.17 kg 

Answer(s): (a) 63; (b) 19.17 kg