Need help with questions I have more

Look at the following graph of the given equation. determine whether the equation is a function. explain why or why not.

Bocephus has a bag full of nickels and dimes. if there are 3 times as many dimes as nickels, and he has $\$36.05$ in his bag, how many nickels does he have?

Josie buys a pair of boots that retail for $52.00 dollars, however they are currently on sale for 25% off how much does josie pay for the boots if there is also a 6% sales tax on them