500 stiches/2/3 min = 750 stiches per minute
Among many other formulas, the area of a triangle is

where B is the angle between sides a and c.

Answer: 92.05 sq cm, first choice
Bonus. Here's a formula for the area S of a triangle your teacher doesn't know:

To determine the coordinates of the midpoints of a line segment, get the average of the both the abscissas and ordinates. In this example, the average of the abscissas is 22 and that of the ordinates is -4. Thus, the midpoint is (22, -4).
Do you want me to find the amount of rectangles in the scarf?