A 6 pound watermelon cost $2.40 before a 30% discount which equation would allow you to find a discounted price of the watermelon

There's 2 easy ways to do it (more than 2, but I find these easy):

First of all, divide the price by 100 to find what 1% is.

Now, you can either multiply by thirty to find how big the discount is and take that away OR you can multiply by 70, seeing as 70% is left once the 30% discount is in effect.