I first write out what we're looking for, then what we know, then try to construct the relationships to decide what we need. For example:
What are we looking for? Remaining money needed
What's the relationship? Remaining money needed = total amount required - money already collected
What do we know? Total cost per person (4500), number of choir members (24)
What do we need? The total Amount Required and the Amount Collected so far
Total Amount Required = cost per person x number of people = 24 x 4500 = 108000
Total Amount Collected = amount of full scholarships given + amount of 1/2 scholarships given = 1/2 choir x 4500 + 1/3 choir x 1/2 (4500) = (12 x 4500) + (8 x 4500/2) = (54000 + 18000) = 72000
So remaining money needed will be (plugging everything in): total amount required - money already collected = 108000 - 72000 = $36000
+4 
