Answer: 110 child tickets and 50 adult tickets were sold.
Step-by-step explanation:
Let x be the number of child tickets and y be the number of adult tickets.
then, According to the given information, we have
[tex]7x+9y=1220------------(1)\\\\x=10+2y----------(2)[/tex]
Substitute the value of x from (2) in (1), we get
[tex]7((10+2y))+9y=1220\\\\\Rightarrow\ 70+14y+9y=1220\\\\\Rightarrow\ 23y=1220-70\\\\\Rightarrow\ 23y=1150\\\\\Rightarrow\ y=\dfrac{1150}{23}=50[/tex]
Now, put the value of y in (2), we get
[tex]x=10+2(50)=110[/tex]
Hence, 110 child tickets and 50 adult tickets were sold.
