Answer:
Total cost is 2,800
Explanation:
The given ratio 5:7:13 represents profit to cost of materials to labour.
However it is stated that cost of materials is Le 840 more than that of labour
Cost of material - 840 = labour
Cost of material = labour - 840
Let
Cost of material be x, and labour be y
x ÷ y = 7 ÷ 13 (equation 1)
x = y - 840 (equation 2)
Substitute x from equation 1 in equation 2
(y - 840) ÷ y = 7 ÷ 13
13 (y -840) = 7y
y = 1,820
Substitute value of y in equation 2
x = 1820 - 840
x = 980
So total cost is cost of material plus cost of labour = 980 + 1820 = 2,800
This will satisfy the ratio of 5:7:13 representing profit to cost of materials to labour