Raj is much better at baking cookies than Jeremy. The ratio of Jeremy's to Raj's cookies became 6 : 67 after Raj baked 21 more cookies. The initial ratio was 1 : 10. Find out the number of cookies that Jeremy had.

The coordinates of the vertices are
(-4, 3)
(0, -3)
(2, 4)
(0, 2)
we can solve for the area of the polygon by using the formula
a = 0.5 | x1 x2 x3 |
              | y1 y2 y3 |
putting the coordinates in a matrix:
a = 0.5 | -4   0   2   0 |
              | 3   -3   4   2 |
getting the determinant
a = 0.5 (12 + 4 - (-6) - (-8))
a = 15

the area is 15 square units