Answer :
The original price of the racket is $30
Markup and discount price
Let the original price be x
If there is 30% off the original price, then the new price will be 0.7x
If the price of tennis racquet is now $21, hence;
0.7x = 21
Divide both sides by 0.7
0.7x/0.7 = 21/0.7
x = 21/0.7
x = $30
Hence the original price of the racket is $30
Learn more on discount here: https://brainly.com/question/19104371