Tickets for the school play cost $12 for adults and $8 for students. On opening nigh 120 tickets were sold and $1300 was collected. How many tickets were sold?

Question

zepp · Answer

Let the number of students tickets be x and the number of adults tickets be y

120 tickets were sold > x+y=120
$1300 was collected > 8x+12y=1300

zepp · Answer

Now you have the system, solve for x, and y.

anonymous · Answer

$x+y=120$
Isolate x
$x=120-y$

Substitute x in the second equation$$\begin{align}8(120-y)+12y&=1300\960-8y+12y&=1300
\960+4y&=1300\
4y&=1300-960\
4y&=340\
y&=340\div4\y=85
\end{align}$$

So 85 adults tickets were sold, what about student? 
Substitute 85 in the first equation
$x+y=120\x+85=120\x=120-85\x=35$

35 Students tickets and 85 Adults tickets were sold.