X= number of adult tickets
y=number of child tickets.
we can suggest this system of equations:
x+y=118 ⇒x=118-y
7.5x+3y=696
we can solve this system of equations by substitution method:
7.5(118-y)+3y=696
885-7.5y+3y=696
-4.5y=-189
y=-189/-4.5
y=42
x=118-y
x=118-42
x=76
Answer: the number of adult tickets sold was 76.
Rick started his coffee break at 9:40 am.
