Question

3 doughnuts and 2 cakes costs £7.
5 doughnuts and 4 cakes costs £13.
Find the cost of a doughnut.
Find the cost of a cake

Answer 1

20 answer because It must be divided by 7 and then multiply by 13

Answer 2

Answer:

doughnuts=x cake=y

1st eq) 3x + 2y = 7

2nd eq) 5x + 4y = 13

.°. 3x = 7 - 2y

x = 7 - 2y / 3 (3rd eq)

5x + 4y = 13

5 (7-2y/3) + 4y = 13

35 - 10y /3 + 4y = 13

35 - 10y + 12y = 39

35 + 2y = 39

2y = 39 - 35

2y = 4

.°. y = 2

now, acc to 3rd eq,

x = 7 - 2y /3

x = 7 - 2(2) / 3

x = 7 - 4 / 3

x = 3 / 3

.°. x = 1