1/ if the fraction is mixed number example 2 1/7, it will be 2x7+1 and that will be 15 over 7
2/and if the bottom number example: 2 1/7, 7 is the bottom number and if 2 1/3 (3 is the bottom number) then see what the bottom number have in common example: 7-x1=7
7x2=14
7x3=21
3x1=3
3x2=6
3x3=9
3x4=12
3x5=15
3x6=18
3x7=21
so 21 is 7 and 3 have in common so the bottom number which is now 21 will divide 7 and got 3 and 3 will go on the top number 1 and 21 divide 3 which is 7 will go on the top number 1 and you continue to add your sum or subtract understand or not