We know that
• The tip is $3 each time.
,• Last month he ate there 6 times.
,• He spent $78 in total.
,• The soda costa $1.50.
Based on the given information, we can express the following
[tex]6(3+1.50+h)=78[/tex]Let's solve the equation for h
[tex]\begin{gathered} 6(4.50+h)=78 \\ 27+6h=78 \\ 6h=78-27 \\ 6h=51 \\ h=\frac{51}{6}\approx8.50 \end{gathered}[/tex]