<span>1.255 times the party bill.
x = party bill
s = sales tax
t = tip
C = total cost = the bill, plus the sales tax, and the tip
C = x + s + t
We know that both the sales tax and the tip are percentages based on the party bill. The sales tax is equal to 7.5% of the party bill. The tip is equal to 18% of the party bill.
so,
s = (0.075)*x
and,
t = (0.18)*x
Then we replace the s and the t in our equation,
C = x + 0.075x + 0.18x
Then, we add the elements together.
C = (1+0.075+0.18)x
C = 1.255x</span>
