# Purchase

Mother bought 5 boxes of milk and 7 kg of potatoes and paid a total CZK 147. Aunt bought 7 boxes of milk and 3 kg of potatoes and paid 131 CZK. What is the price of one carton of milk and 1 kg of potatoes? How CZK together would have saved if bought at the supermarket, where they have the same price of milk, but the potatoes is 20% cheaper?

Result

x =  14
y =  11
z =  22

#### Solution:

5x+7y = 147
7x+3y = 131
z = 0.2(3+7)*y

5x+7y = 147
7x+3y = 131
2y-z = 0

x = 14
y = 11
z = 22

Calculated by our linear equations calculator.

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