The cost of 2 bottles of water and 4 apples is $5.50. The cost of 3 bottles of water and 5 apples is $7.50. Find the cost of one apple and the cost of one bottle of water.

$3.50

Step-by-step explanation:

Because the cost of 2 bottles of water & 4 apples is $5.50, & the cost of 3 bottles of water & 5 apples is $7.50.

If you look a it from the way I am then you would see that the .50¢ never changed its value correct?

But the $5 changes to $7 so what I'm thinking is that the $5.50 added $2.00 to get $7.50 so I think if you SUBTRACT $2.00 from the $5.50 then you would get the same answer.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18