Explanation:
always remember that 100% is the whole.
so, 15% means 15/100 of the whole.
1/5 = 0.2 = 20/100 of the whole.
so, Target is taking 15/100 off the price.
Walmart is taking 20/100 off the price.
20/100 is bigger than 15/100, so Walmart deducts more off the price, and has therefore the lower and therefore better sale price.
Target sale price :
100/100 - 15/100 = 85/100 × 80 = $68
in short
80 × (1 - 0.15) = 80 × 0.85 = $68
Walmart sale price :
100/100 - 20/100 = 80/100 × 80 = $64
in short
80 × (1 - 0.20) = 80 × 0.80 = $64