A knife is three times the cost of a spoon.
9 spoons and 12 knives cost £82.80.
Work out the cost of 1 knife

cost of knife = £5.52

Step-by-step explanation:

Assume:

Cost of Knife = a

Cost of Spoon = b

a = 3b   (1)

12a + 9b = £82.80 (2)

Substitute equation (1) in equation (2)

12 * (3b) + 9b = £82.80

36b + 9b = £82.80

45b = £82.80

b = £1.84

Therefore, cost of knife = a = 3 * £1.84 = £5.52

i think it would be c

mark brainliest if im right

step-by-step explanation: