What you would do is take the denominators and multiply them by each other, then multiply the numerators by that same number. So like 4/10 and 4/9. You would say, (denominators) 10x9=90 and (numerators) 4x9=36. So your first fraction would be 36/90. Next, you would take (denominators) 9x10=90 and (numerators) 4x10=40. So your second fraction would become 40/90. Now it's a lot easier to compare. 36/90 < 40/90 would be the answer to my problem. I hope I helped!