15y is less than 36+9
y is less than 45/15
y is less than 3
et balcony tickets be represented by 'b' & main floor tickets by'm'.
There were 100 more balcony tickets than main-floor tickets sold for a concert.
-->> b-m=100...(eq. 1)
From the second condition we get...
-->> 4b+12m=3056...(eq. 2)
multiply eq1 by 12 and add it with eq.2
-->(12b-12m)+(4b+12m)=(1200+3056)
-->16b=4256
-->>b=266
so 266 balcony tickets were sold.
hope this helps
