Victor has 40 kg of pinto beans which cost $0.69 per kilogram. How many kilograms of kidney beans at $0.89 per kilogram should be added for the complete mixture to have a value of $0.81?

Let the amount of kidney beans to be added be X kg

Cost of X kg kidney bean = $0.89X

Cost of 40 kg pinto bean = $40*0.69 = $27.60

Total amount of the mixture = (40+X) kg

Cost of mixture per kg = $0.81

Total cost of the mixture = $ (40+X) * 0.81

According to question pinto bean and kidney bean are mixed.

Thus,

27.60+0.89X = (40+X) 0.81

Removing the parenthesis

27.60+0.89X = 32.4 + 0.81X

Taking like terems together

32.40 - 27.60 = 0.89X - 0.81X

4.80 = 0.08X

X = 4.80/0.08

X = 60kg

Therefore 60kg of kidney beans to be addes to the mixture