Czech coins

John has 540 CZK, but he has 10 CZK coins and 20 CZK coins only, we knows that he has 10CZK coins 7times more that 20CZK coins, how many 10CZK coin and how many 20CZK coins he saved?

Correct answer:

a =  42
b =  6

Step-by-step explanation:


10a+20b=540
a=7b

10•a+20•b=540
a=7•b

10a+20b = 540
a-7b = 0

a = 42
b = 6

Our linear equations calculator calculates it.



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