i have another question on this topic.

a rectangular building is to have an area of 1800 sq. meters. on each side of the building there must be a walkway of 5 meters and on each end a walkway of 10 meters. What is the dimensions of the smallest rectangular piece of land that can accommodate the building?

so, i tried

area = xy

= (x-5)(x-10)

1800 = (x-5)(x-10)

= x^2 - 15x +50

0 = x^2 - 15x - 1750

doesn't seem to be im doing correctly...

what should i do?