5x+9z-x
5x-x+9z
4x+9z
Equivalent expression is asking for you to simplify by adding like terms and eliminatino parenthesis. Use the PEMDAS.
for a all you have to do is * you will find the answer. for b what ever yo answer was for a u will put that for the hours n what u had * u put for min for seconds
D because the submarine started at sea level and ended 400 meters BELOW sea level.