We assume all money is spent on new lighting. Since they currently have $160 and need $400 we can subtract what they currently have from what they need.
$400-$160 = $240
Since we know the price of the ticket and now know they need $240 we can divide our $240 with the price of each ticket ($3)
$240/$3 = 80
So the drama club has to sell 80 more tickets in order to afford new lighting
Answer: C
Step-by-step explanation:
and 
1/2 + 1/3 = 3/6 + 2/6 = 5/6
we have 5/6 so 15 is 1/6 of the entire group
15 × 6 = 90
