SOLUTION: Rachel piggy bank consists of P10 and P5 coins only. If there are 75 coins worth P450.How coins are there in the piggy bank?

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Question 957149: Rachel piggy bank consists of P10 and P5 coins only. If there are 75 coins worth P450.How coins are there in the piggy bank?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
X - number of P10 coins
Y - number of P5 coins
.
.
.
X%2BY=75
10X%2B5Y=450
Multiply first equation by 10 and subtract from second equation.
10X%2B5Y-10X-10Y=450-750
-5Y=-300
Y=60
Then,
X%2B60=75
X=15