Question 898123
d for dimes
q for quarters
q=-4+d or q=d-4


Amount of money is {{{0.1d+0.25q}}} dollars, or by substitution for q,
amount of money is {{{0.1d+0.25(d-4)}}}
{{{0.1d+0.25d-1}}}
{{{highlight(d-1)}}}.


You wanted x to represent the count of dimes, so you use this instead and say the amount of money is x-1.