Let us consider that the hydrogen , oxygen and methane are present in 100 grams proportion.
Since the volume of gas is directly proportional to number of moles of gas
The molar mass of hydrogen oxygen and methane are 2 gm/mol , 32 gm/mol and 16 g,/mol respectively.
Step 1 - Calculation of number of moles
Numberofmolesofhydrogen=GivenmassingramsMolecularmass=1002=50moles
Numberofmolesofoxygen=GivenmassMolecularmass=10032=116
Numberofmolesofmethane=GivenmassMolecularmass=10016=18
Theratioofvolumeofhydrogenoxygenandmethanewillbehence
1002:10032:10016=11:116:18=16:1:2