Answer:
100 years old
Step-by-step explanation:hope it helps:)
Let x be the width of the sidewalk and the area becomes:
A=LW and L=6+2x and W=4+2x now we have
A=(6+2x)(4+2x) and we are told that A=48ft^2
48=24+20x+4x^2
4x^2+20x-24=0
4(x^2+5x-6)=0
x^2+5x-6=0
x^2-x+6x-6=0
x(x-1)+6(x-1)=0
(x+6)(x-1)=0
So x=-6, 1, however since x is a measurement it must be positive thus
x=width=1 ft is the only possible solution.
It is given in the question that B is in between C and D.
Therefore

Substituting the given values of CB,BD and CD, we will get

Combining like terms, we will get

Now we need to move 4 to the right side by adding 4 to both sides, that is
