Answer: C. 28 adult tickets; 42 child tickets
Step-by-step explanation:
Let x = Number of child ticket
y= Number of adult tickets
As per given , we have the following system of linear equations :
[tex]x+y=70---(1)\\\\ 8x+12y=672----(2)[/tex]
Multiplying 8 on both sides of equation (1), we get
[tex]8x+8y=560----(3)[/tex]
Subtract (3) from (2) , we get
[tex]4y=112\\\\\Rightarrow\ y=\dfrac{112}{4}=28[/tex]
Put value of y in (1) , we get
[tex]x+28=70\\\\\Rightarrow\ x=70-28=42[/tex]
Hence, the correct answer is
C. 28 adult tickets; 42 child tickets
