Respuesta :

check the picture below.

notice, the paralleogra is really just two triangles, with a base of 7 and a height of 3.

get the area of each triangle, sum them up, and that's the area of the parallelogram.  Recall that for a triangle A = 1/2 bh.
Ver imagen jdoe0001

21 my doodles. (3*7)/2+(3*7)/2 = 21

Do what the dude below me did and get the two triangles