Problema Solution

Bob has five centavo and twenty-five centavo-coins that total P4.20. He has twice as many five-centavo coins as twenty -five coins. How many twenty-five centavo coins has BOb?

Answer provided by our tutors

let


x = the number of five centavo coins

y =the number of twenty-five centavo coins


He has twice as many five-centavo coins as twenty -five coins


x = 2y


the total money he has is 4.20 = 420 centavo


5x + 25y = 420 divide both sides by 5


x + 5y = 84


by solving the system of equations


x = 2y

x + 5y = 84


we find


x = 24 coins


y = 12 coins


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Bob has 24 five centavo and 12 twenty-five centavo coins.