Question

Two stock pens are to be built next to each other, with one side of each being against an existing wall (see the figure). The width is x meters. The total amount of fence material to be used is 100 meters
a) Write a expression for the total length, indicated in the diagram
b) What overall length will the pens be if they are 10 meters wide?
c)How wide will the pens be if they are 30 meters long over-all?
d) How wide will the pens be if the width is one-third the over all length?

Answer 1

Let length of pens=l
Amount of fencing to be done = 2x + l= 100

a. Hence the total length is l= 100 -2x

b. If x= 10m ten l =100-2*10= 80m

c. If l=30 then 2x= 100 - 30=70
                   ⇒ x=35 m

d. If x=l/3 then l=3x
   we have 3x=100-2x
             ⇒ 5x=100
                 x=20 m

Answer 2

length = l 
amount of fencing to be done = 2x + l = 100
a) total length =  2x + l = 100
l = 100-2x
b) if x - 10 = 0
x = 10
overall length = 100 - 2x10 = 100-20 = 80
c) l = 30 
l = 100-2x
2x = 100 - 30
2x = 70
x = 70/2
x = 35
d) if x = l/3
l = 3x
then 3x = 100 - 2x
3x + 2x = 100
5x = 100
x = 100/5
x =20