Answer:
a) The amount of edging needed = 7.54 meters
b) Cost to edge the garden = $32.80
Explanation:
a)
the amount of edging needed is basically the circumference (perimeter) of the circle. It has the formula:

Where
C is the circumference
r is the radius
Given, diameter = 2.4, radius is HALF of it, so
r = 2.4/2 = 1.2
Now, finding circumference:

The amount of edging needed = 7.54 meters
b)
$4.35 is needed to edge 1 meter, since we need 7.54 meters, we find the total cost by multiplying 4.35 with 7.54, so we have:
4.35*7.54 = $32.80
Cost to edge the garden = $32.80