1. The problem statement, all variables and given/known data There are x boys and y girls in a class(Class A) The girls outnumber the boys by 4. They join up with another class(Class B) in which there are twice as many boys as girls. Class B has 3 more boys and 5 less girls than class A. Which one of the following systems of equations can be used to solve for x and y? 2. Relevant equations 1. y-x=4 2y-x=8 2. y-x=4 2x-y=-13 3. y-x=4 2y-x=13 4. x-y=4 2x-y=13 5. y-x=4 x+2y=7 3. The attempt at a solution y-x=4 y=x+4 x=y-4 x-y=-4 Class B (a)boys = x+3 (b)girls= y-5 a=2b b=b/2 x=b-1 x=a+3 y=b+5 y=a-1 Considering the above the answer must be: y-x=4 this means option 2 is not possible. Option 1 also doesn't seem to work. Option 5 doesn't make sense to me. I am leaning towards option 3 or 4 x+y+a+b=z I feel like this should be simple but I am just not getting it. Input would be appreciated. Thank you everyone.