4/5 would be 32/40 in simplest form.
To find the simplest form of 32/40 you would have to find the least common multiple of 32 and 40.
You can keep on adding until you find a common multiple.
32 64 96 128 160
40 80 120 160
After you find the least common multiple (160), you divide 32 and 40 by 160.
160÷32=5
160÷40=4
4 would be your numerator and 5 would be the denominator. So, you would get the fraction 4/5 as your answer.
