Audrey B. answered 12/02/20
UF Graduate Teaches Math and Science
First, express the side lengths of the field as algebraic expressions. The length is an unknown variable, and the width is six meters less than that variable.
L = x
W = x - 6
Now, we know the value of the perimeter when each of these values is doubled is 120 meters. So, first we need to double the side lengths.
2L = 2x
2W = 2(x - 6) = 2x - 12
Now we write an expression that will tell us the perimeter of this hypothetical field with the doubled side lengths. You probably know that a perimeter is twice the width plus twice the length, so the width of this doubled field will be:
P = 2(2x) + 2(2x - 12) = 4x + 4x - 24 = 8x - 24
We know the perimeter of this doubled field is 120 meters, so now we know:
120 = 8x -24
Now solve the equation.
144 = 8x
x = 18
Now we know that the length of the original field is 18 meters. The width is 6 meters less than the length, so we know the width is 12 meters.