The amount of material needed by Marta to make the flag is;
square inch.
The total cost of making the flag is;
dollar.
Given
Marta is making a flag with the given dimensions.
The perimeter of the flag is 100 inches.
Let us consider that the flag has a triangular shape.
<h3>Hero's formula;</h3>
According to the Hero's formula;
The area of the triangle is given by;

Where, s is the semi perimeter and a, b, and c are the sides of the triangle.
Semi perimeter s = P/2,
Since the perimeter of the flag is 100 inches.

The dimensions of triangular shape are
.
Then,
The area of the triangular flag becomes;

So the amount of material needed to make the flag is;

Therefore,
The cost of material = C = $0.15 per square inch
So the total cost in making the flag will be;
.
Hence, The amount of material needed by Marta to make the flag is
.
To know more about Hero's formula click the link given below.
brainly.com/question/24399817