Answer:
20 feet
Explanation:
The area formula is lw=A, where l is the length, w is the width, and A is the area. So, plug in the known variables. This creates the equation l15=300. Then, solve for l by dividing both sides by 15. Therefore, l=20. You can check your answer by plugging in all of the variables to create the equation 20*15=300. This is a true statement, thus 20 feet must be the correct length.