First you multiply the numerator and denominator. So 1 times 2 is 2. And 8 times 5 is 40 and then you simply it is 1/20 because 2 divide 2 is 1 and 40 divide 2 is 20 so it is 1/20.
1/8 plus 2/5=you dot know yet so let me explain to you ok alright 5 can not go into 8 and 8 can not go into 5 so what you need to do is make the denominator 8 times 5 which equals 40. 40 will be both of the denominators then you will do 8 times 2 equal 16 then you will do 5 times 1 which equal5.1/8 is now5/40and2/5 is now 16/40 then you will multiply but when you fro keep the 40 and multiply the numerator .You may have to simplify.