[AWK]

Stoichiometry is an absolute beginning of chemical calculations. The only chemistry -  balanced reaction is known from elsewhere, the rest is  a simple algebra.
Without calculator in a few seconds I got for H₂O:CH₄ ratio 2.4:0.4 which is for methane to water ratio ...

[greenwoodturner]

It's simple algebra and a no-brainer problem ... when you understand the problem space.  That was something I was never able to get across.  Regardless, I found a friend who was willing to take the time to work through the problem with me, so that I can now understand it and explain it to my daughter.

[AWK]

Take the same problem with others H₂O:CH₄ ratios
1:1 answer is 1:1
1:1.4 - 2:1
1:1.8 - 3:1
1:2.2 - 4:1
1:2.6 - 5:1
CH₄ + H₂O = CO + 3H₂
60 % conversion
CH₄ + H₂O = 0.6CO + 1.8H₂ + 0.4CH₄ + 0.4H₂O

CH₄ + 1.4H₂O = 0.6CO + 1.8H₂ + 0.4CH₄ + 0.8H₂O
and so on
Note: in your question methane and water is interchanged!

[greenwoodturner]

Thank you ... your last explanation was very clear and made sense.  Same answer as what my friend got, but your's was a slightly different (and more intuitive) approach.  I will pass it onto Ramona.  Thank you very much for your *delete me*