We have the next information
x= the shortest side measure
y= the second side measure
y=x+100
z= the third side measures
z=x+700
We know also that the perimeter is 2900 ft
Therefore the equation for the perimeter of the triangle will be


we sum like terms

then we isolate the x



therefore
x=700ft
y=700+100=800ft
z=700+700=1400ft
The lengths of the sides of the lote are 700 ,800, and 1400 ft,