A submarine on the surface of the ocean descended at a rate of 7 feet per second for 2 minutes. Then it ascended at a rate of 4 feet per second for 3 minutes, Finally, it descended at a rate of 9 feet per second for 5 minutes. What was the final elevation of the submarine?

I believe the answer is 2,820 feet.

Step-by-step explanation:

First, you would need to multiply 60 by however many minutes to see how many seconds there are.

Second, multiply the number of feet by the seconds you found from the first step.

Lastly, add together the two descending part. Then subtract it from the ascending part.

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.