Math (Algebra/PreAlgebra)
posted by Samantha .
A book has been discounted 20% and now sells for $15. How much did it cost before the discount?

After we took off 20%, doesn't the $15 represent 80% of what it used to cost?
so .8x=15
x = 15/.8
= 18.75
test the answer by taking 20% of that, and subtracting it.
Do we get $15 ? 
That is one of the choices so my guess is that that is correct. Thank you! =]

8=1/4x6