Solve this 3 variable system of equations
2g + 3h - 8j= 10
g - 4h =1
-2g - 3h+ 8j= 5

Not solvable. If you take the first and last equations together, then multiply the last by -1 you get
2g+3h-8j=10
2g+3h-8j=-5
Resulting in
10=-5, which is false, so there is no solution

The correct answer would be "convenience"

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction