Tim has some marbles.

Sue has twice as many marbles as Tim.

Jim has 15 marbles.

Tim, Sue and Jim have a total of 63 marbles.

How many marbles does Tim have?

Tim has about 24 marbles.

If Jim has 15.

And they all have 63.

63-15=48

48 divided by 2 is 24.

We can solve this by setting up an equation. I am setting the amount of marbles that tim has as T. Because Sue has twice as many marbles as Tim, she will have 2T marbles. We do not need a variable for Jim, because he has 15 marbles. Now, we can set up this equation:

T + 2T + 15 = 63

Now, we can solve for T. First, we subtract 15 from both sides.

T + 2T = 48

Next, we combine all the T terms.

3T = 48

Finally, we divide both sides to find how many marbles Tim has.

T = 16

So, Tim has 16 marbles.