need to know what is left in the bag after some poured into canister which gives the canister 2 times the mass over the bag

In order to answer this question we need to rewrite the word problem as a formula.

Start with the values they give you, 5026 and 4125. This is the total amount of flour. The flour will then be split so that 2 times as much is in the canister than in the bag, 2x and x.

From this you can set up a formula that sets the total amount of flour equal to the final amounts in the canister and bag:

5026 + 4125 = 2x + x

9151 = 3x

9151/3 = 3x/3

3050.33 = x

Since x was the amount left in the bag the answer will be 3050 and 1/3 (3050.33)