Xavier bought 3 times as many white chocolate bars as dark chocolate bars. The total mass of white chocolate bars and dark chocolate bars was 1146 g. The mass of dark chocolate bars was 186 g less than that of the white chocolate bars. The mass of 1 dark chocolate bar was 43 g heavier than 1 white chocolate bar.

1. Find the number of white chocolate bars that Xavier bought.
2. Find the mass of 1 dark chocolate bar.

	White Chocolate Bars	Dark Chocolate Bars	Total
Number of sets	3 sets	1 set
Compare each	1 u	1 u + 43
Total value	666 g	480 g	1146 g

(a)
Mass of dark chocolate bars = 1 set
Mass of white chocolate bars = 3 sets

Mass of dark chocolate bars = (1146 - 186) ÷ 2 = 480 g
Mass of white chocolate bars = 480 + 186 = 666 g

Mass of 1 set of dark chocolate bars = 480 g
Mass of 1 set of white chocolate bars = 666 ÷ 3 = 222 g

Difference in the mass between 1 set of dark chocolate bars and 1 set of white chocolate bars
= 480 - 222
= 258 g

Number of items in each set
= 258 ÷ 43
= 6

Number of white chocolate bars
= 3 x 6
= 18

(b)
Mass of 1 dark chocolate bar
= 480 ÷ 6
= 80 g

Answer(s): (a) 18; (b) 80 g