Answer :

49/84   49: divid it by 7 and it will equal to 7
           84: divid it by 7 also and that will equal 12 

so your answer will be 7/12


to simplify , you find the ones  exg 4//8=1/2 because 1/2 times 4/4=4/8

so we find the factors

49=7 times 7
84=7 times 12

49/84=7/7 times 7/12

simplified to 7/12