**Answer:** 3.

If we denote Alex by A, Blake by B, Charlie by C and Drew by D we can find the answer in the following way.

Since A + B + C = D and A + B + C + D = 44, it is easy to see that D has 22 sheep.

So A + B + C = 22.

We can use this along with the two other facts, A + 3 = B - 1 and C - 3 = 3A, to find that A has 3, B has 7, C has 12 and D has 22.

In a little more detail:

A + B + C = 22 (1)

A + 3 = B - 1 (2)

C - 3 = 3A (3)

Rearrange (3) to give C = 3A + 3 and replace the C in (1) to give A + B + 3A + 3 = 22.

Simplified this gives B = 19 - 4A (4).

Rearrange (2) to give B - A = 4.

Use (4) in the place of B to give 19 - 4A - A = 4 to give A = 3.

Now use A to work out B, and then C.