Question 503639
P = perimeter = sum of the sides
a = shortest side
b = a+200
c = a+500
.
a+b+c = 1900
.
substitute
.
a +a+200 +a+500 = 1900
3a +700 = 1900
3a = 1200
a = 400
.
b = 400+200 
b = 600
.
c = 400+500
c = 900
.
The three sides of the traingle are:
400 ft
600 ft
900 ft
.
Done.