And then add the two together: $65 + $16.25 = $81.25
You can also do it another way by realizing that in total they payed 125% of what the dinner cost: [tex]Total=125\%\timescsot[/tex] [tex]T=1.25c[/tex] [tex]T=1.25\times65[/tex] [tex]T=$81.25[/tex] same as above.