Question

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?

Answer 1

Money they have initially altogether = 28

Explanation:

The ratio of money in Obi's wallet to Rudy's wallet one day was 5:2.

Money Obi has = 5 r

Money Rudy has = 2 r

Obi spent 20 that day and bi now had 8 less than Rudy

5r -20 = 2r - 8

3r = 12

r = 4

Initial money they have

Obi = 5r = 5 x 4 = 20

Rudy = 2 x 4 = 8

Altogether they have 20+8 = 28

Money they have initially altogether = 28

Answer 2

Altogether, they had ?28

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.