If you get 4 bottles of wine, you get a 20% discount. 2 of the bottles are $12.00 each. How expensive do the other two bottles have to be to make the 2 $12.00 bottles "free"?

Answer 1

If they cost $x each, then you need
0.80 (2*12 + 2x) = 2x

Answer 2

.8 ((2)(12)) + .8 (2x) = 2x
19.2 + 1.6x = 2x
1.6x + 19.2 = 2x
1.6x + 19.2 - 2x = 2x - 2x
-.4x + 19.2 = 0
-.4x + 19.2 - 19.2 = 0 - 19.2
-.4x = -19.2
-.4x/-.4 = -19.2/-.4
x = 48
So the two bottles will be expensive by $48 to be able to make the 2 $12.00 bottles "free"