The ratio of money in obi's wallet to rudy's wallet one day was 5: 2. obi spent ? 20 that day. obi now had ? 8 less than rudy. how much did they have initially altogether?

  Altogether, they had ?28

Step-by-step explanation:

Had Obi spent only ?12, they would have been even. Thus ?12 is the same as 5-2 = 3 "ratio units". So, each "ratio unit" is worth ?12/3 = ?4.

Then Obi started the day with 5·4 = 20, and Obi started the day with 2·4 = 8. Obi ended with 0, which is 8 less than Rudy.

Altogether, they started with 20 + 8 = 28 of whatever a ? is.