It is a hard one :)
Caleb had 37 more marbles than David at first. Caleb gave away 4 times as many marbles as David.
Start with 2x+37 marbles, then give away 5y marbles.
So how much do they each start with?
How many do they give away?
What are they left with?
Work out what Calab and David will be left with SEPERATELY
These will both be expressions with x and y
David was left with 5 more than the number of marbles he gave away.
Caleb had twice as many marbles left as David. How many marbles did Caleb have in the end?
Use these two sentences to form 2 simultaneous equations. Then solve.
etc