Question 1128219
The number of gumballs that can be bought 
with {{{ q }}} quarters before tax is;
{{{ ( 25q )/x  }}}
After tax, the number is:
{{{ ( 25q - z )/x }}}
----------------------------
check:
If {{{ q = 10 }}}
{{{ x = 10 }}}
{{{ z = 50 }}}
then
{{{ ( 25*10 - 50 )/ 10 = 20 }}} gumballs