21. The number of bricks, B, needed to build a wall of length L feet and uniform height H feet can be found by the equation B = 7LH. A wall of uniform height that is 30 feet long is constructed using 420 bricks. What is the height, in feet, of the wall?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

Substitute the relevant data into it to get 420=7×30×H, and get the value of x to be 2. Choose C.