Plz plz plz plz help me plz it is due in 1 hour and no links plz​

The polygon tool to draw a rectangle with a length of 5 units and a height of 3 units. one of the sides of the rectangle falls on line ab , and the rectangle has a vertex of a. each segment on the grid represents 1 unit.

What is the area of the triangle 10 13 12

Apackage of five erasers cost 0. $.39 at this rate how many how much would 60 erasers cost in dollars and cents