First find the area of the rectangle by multiplying Base x height. 17 x 13 = 221
Now to find the area of the huge triangle, you have to do (Base x height) / 2. So your height would be 8. Now your base would be the same as the length of the rectangle which is 17. (17 x 8) / 2 = 68
Multiply the numerators: 7×8=56 then the denominators 10×21=210. The lowest multiples for 56 and 210 is 14. So divide 56/14=4 and 210/14=15. Your answer is 4/15.