First, convert the kilograms to grams. One kilogram is 1000 grams. So multiply it by 1000. Then subtract 2305 from 4000. 4000-2305=1695. So 1695 grams were taken out.
So we are given a system:

Substitute x = 2 we get the system:

Multiply the first equation by -5 and the second by 2 we get the system:

Adding the two equations we get :

We find the value of y by using any of the other equations like this:

Final solution: