To answer this question, we must first represent the given facts in an equation.
Alex = A
Bob = B
Carl = C
Now,
A + B + C = 3,750
We should first find out how much Bob or B has:
A = 0.5(50%)B + B = 1.5B
C = 0.25(25%)B + B = 1.25B
Substitute aforementioned values to A + B + C = 3,750 :
1.5B + B + 1.25B = 3,750
3.75B = 3750
B = 1000
Bob has 1000. Therefore, Carl has 1250 and Alex has 1500
To check:
1000 + 1250 + 1500 = 3750