Silas had some money at first. His mother gave him another $6 and he spent $20 on a book. As a result, the ratio of the money he had at first to the money he had in the end was 10 : 3.
(a) Find the difference between the amount of money Silas had at first and the amount of money Silas had in the end.
(b) How much money did Silas have at first?
Silas at first = S
Silas had 20 at first and he had 6 in the end.