Answer:
15m
Step-by-step explanation:
Well, she needs 120 meters, which means we already know the circumference (P). P is the sum of all sides.
The lenght (a) is 3 times the width(b).
a = 3b.
Which means if a is x then b is equal to 3x
Since P is the sum of all sides, P is equal to 2a + 2b or 2x + 2*3x = 2x + 6x = 8x
120 = 8x. We are now left with an equation that has one variable only, all we need to do is to divide 120 by 8 to find what x is equal to.
8x = 120
x = 120 / 8
x = 15
We know that width(a) is equal to x, so that's the answer.
Here's a solution you can write:
P = 120m
w = x
l = 3w = 3x
P = 2w + 2l
P = 2*x + 2*3x
P = 2x + 6x
P = 8x
8x = 120
x = 120 / 8
x = 15
w = x -> w = 15m
