Write an equation to represent the function and solve Mrs Lu

Write an equation to represent the function and solve: Mrs. Lundquist is buying tickets for an upcoming Wild game. The cost of each ticket is $75 and there is a service fee of $12. Let n represent the number of tickets she will buy and f(n) represent the total cost of purchasing the tickets. Write an equation to represent the function(no spaces): How much will Mrs. Lundquist pay if she buys 3 tickets? How many tickets did Mrs. Lundquist buy if she paid $537?

Solution

Here Given in question ,

Cost of each ticket is $75 and service fee is $12 so, we can write function of grand total:

f(n) = $75*n+$12*n ;where n is number of ticket

if Lundquist buy 3 tickets then n=3 ;

f(3) = $75*3+$12*3=225+36 = $261

f(n)= $537

then  Lundquist bought :

$537/87 = 6.17 =6 tickets