Question

sally has a piggy bank with $10 in it. She counted 68 coins of only quarters and nickles. How many nickles are in her piggy bank?

Answer 1

n=35; q=33 coins.

Explanation:

1) if number of nickles is 'n' and the quaters is 'q' then it is possible to write:

n+q=68 - 'she counted 68 coins...' - the 1st equation of system;

0.25q+0.05n=10 - '10$ in it' - the 2d equation of the system.

2) it is possible to make up and solve the next system of two equations:

`\left \{ {{q+n=68} \atop {0.25q+0.05n=10}} \right. \ => \ \left \{ {{q=33} \atop {n=35}} \right. .`