Three types of bread flour, U, V and W come in containers of 90 g, 180 g and 210 g respectively. Containers of U, V and W are mixed together in the ratio 3 : 6 : 7 to obtain 25.38 kg of an assortment of bread flour.

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

	U	V	W
Number	3 u	6 u	7 u
Value	90	180	210
Total value	270 u	1080 u	1470 u

(a)
Total mass of bread flour
= 270 u + 1080 u + 1470 u
= 2820 u

2820 u = 25380

1 u = 25380 ÷ 2820 = 9

Total number of containers of U and V used
= 3 u + 6 u
= 9 u
= 9 x 9
= 81 

(b)
Combined weight of all the bread flour in containers V and containers W
= 1080 u + 1470 u
= 2550 u

Difference between the combined weight of all the bread flour in containers V and containers W as compared to the bread flour in containers U
= 2550 u - 270 u
= 2280 u
= 2280 x 9
= 20520 g
= 20.52 kg 

Answer(s): (a) 81; (b) 20.52 kg