A submarine is located at 20 feet below sea
level. It rises 5 feet, but
then descends 18 feet.
What is the depth of
the submarine?

Step-by-step explanation:

Time taken to travel 20 m = 1 min

Time taken to travel 360m = x min

add all the numbers and check the ones place.

the answer is 486. as the ones place is more than 4, the estimation will be the next 10 ie, 490

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2