Kali, Kali... How can we help if you show no work? Bad call.

Rule #1 - Name stuff

x = length of pool sides

y = length of pool ends

It's rectangular, so both ends and both sides arr the same, right?

Now Translate!

"A rectangular swimming pool is to be built with an area of 1800 square feet"

x*y = 1800 - Done!

"The owner wants 5-foot wide decks along either side "

5 + y + 5 = 10 + y = length of property ends

"10-foot wide decks at the two ends"

10 + x + 10 = x + 20 = length of property sides

Note: If you have not yet created a drawing to demonstrate this, please do so now. You must be convinced that the measurements are correct. If it should be y + 20 and x + 10, we're barking up the wrong tree.

"Find the dimensions of the smallest piece of property "

The area of the property is A(x,y) = (10+y)(x+20)

As the two variables are a little irritating, perhaps, we have a provision to get rid of one of them. Remember this x*y = 1800? Solve for y.

y = 1800/x

Substitute into the Area function, giving A(x) = (10 + 1800/x)(x+20)

Where does that leave us?