If the center is 3/5th of the entire fly, then that would leave only 1/5 olive on either end of the fly. .....2/5ths...../...1/5th../.....2/5ths.....= 5/5ths.
You are correct though. The third 1/5th is only a 5th of the fly, and it's in the center. ......Olive......./....Red.../.......Olive......