Solution to Rectangle triangle problem

1. Perimeter of rectangle is 56cm, and AB is 18cm. Therefore dimensions of rectangle is 10cm by 18cm.
2. From this we can figure out the area of triangle AEB, which is 18 times 10, divided by 2, to give 90 cm^2.
3. Triangle AEB consists of triangles AFB and BEF, We know that AFB is 42cm^2 , so to find BEF we subtract ABF from 90, which is 90-42, which will give you 48cm, the area of BEF.