x+y=10
x+2y=14
x is common in both so u have to subtract the second one from 1st
x-x + y-2y = 10-14
-y = -4
y=4
which means bottle of water (y) = 4
and then substitute 4 in equation (x+y=10 or x+2y=10)
x + 4 = 10
x=6
Third one down. you can tell just by the first two coordinates
I'd say the bottom answer is the best answer
