Let x be the original price. Then the discounted price is
discount = x(1 - 0.85)
The discounted price is $18.00. Therefore
18.00 = x(0.15)
x = 18.00 / 0.15
x = $120.00
The amount she saved is $120.00 - $18.00 = $102.00
The answer to this question is that Ella saved $102.00.