Q8 q2.) what are the lot's dimensions?

Equation for perimeter is 2L +2W

perimeter of the lot is 390 ft

 so we have 390 = 2L +2w

divide all terms by 2:

195 = L + W

rewrite this as L = 195-W  ( eq.1)

 cost of fence for the length = 36 per foot so we have 36L
cost of fence for width = 6 per foot so we have 6W

the fence was 1 length and 2 sides
 so we have 36l + 6w +6w = total cost

total cost is 4980

so we have 4980 = 36L + 6w +6w

combine like terms:

4980 = 36L +12w

replace L with eq1 from above:

4980 = 36(195-w) +12w

distribute:

4980 = 7020 -36w +12w

combine like terms:

4980 = 7020-24w

subtract 7020 from both sides:

-2040 = -24w
 divide both sides by -24:

-2040 / -24 = 85
width = 85 feet

using eq1 L = 195 - 85

Length = 110 feet

lond = 110 feet
 short = 85 feet