Answer:
40 cookies was sold
Explanation:
Let x represent the number of cakes baked, y represent the number of cookie baked and z represent the number of buns baked.
He made 270 cakes. Therefore x = 270
28% of the total baked products where cookies, hence:
0.28(270 + y + z) = y
75.6 + 0.28z = 0.72y
0.72y - 0.28z = 75.6 (1)
The number of cakes was three times the number of buns. Hence:
x = 3z
3z = 270
z = 90
Put z = 90 in equation 1:
0.72y - 0.28(90) = 75.6
0.72y -25.2 = 75.6
y = 140
Therefore 270 cakes was baked, 140 cookies was baked and 90 buns was baked.
He sold 40 buns and 120 cakes, the number of buns and cakes left is 50 buns and 150 cakes. Let us assume that number of cookies left was a. Since the ratio of left buns to cakes to cookies is 1:3:2. Hence:
(1/6) * (50 + 150 + a) = 50
300 = 200 + a
a = 100
Therefore 100 cookies was left. The number of sold cookies = 140 - 100 = 40