Answer: The original price of the shorts was $25.
Step-by-step explanation:
Let the original price of the shorts be x
Reduced price = 20%
New price will be
[tex]x-20\%x=x-0.2x=0.8x[/tex]
Rate of sales tax = 5%
So, Amount of tax will be given by
[tex]5\%\ of\ 0.8x\\\\=\frac{5}{100}\times 0.8x\\\\=0.04x[/tex]
Amount after tax will become
[tex]0.8x+0.04x\\\\=0.84x[/tex]
According to question, it becomes,
[tex]0.84x=\$21\\\\x=\frac{21}{0.84}=\$25[/tex]
Hence, the original price of the shorts was $25.