Question 721078
University Theater sold 445 tickets for a play.  Tickets cost $20 per adult and $12 per senior citizen.  If total receipts were $6156, how many senior citizen tickets were sold?

a=adults
s=seniors

a+s=445
20a+12s=6156
  
20a+12s=6165
a  +  s  = 445
19a  + 11s=5711       Don't know what else to do.
==========================
a + s = 445
20a+12s=6156
----
Multiply the 1st eqn by 12
12a + 12s = 5340
20a + 12s = 6156
-------------------- Subtract
-8a = -816
a = 102