Answer: She should have multiply each of the sides the scale value before multiplying to find the area.
Explanation:
They are two sides to the triangle which is the base and the height and each side have a different length so you will have to first multiply each side length by the scale value to find the new length of the enlarged triangle.
base: 4 *5 = 20
height : 3.5 * 5 = 17.5
Now since the base is 20 cm and the height is 17.5 cm you will use the area of a triangle formula to solve for the area.
A = 1/2* b * h
A = 1/2 * 20 * 17.5
A = 10* 17.5
A = 175
or she could have multiply 35 which is the number he obtained by another 5 to find the area.