Siti started a savings plan by putting a coin in a money box everyday. Each coin is either a 20-cent coin or a 50-cent coin. Her mother also put in a $1 coin in the box every 5 days. The total value of the coins after 68 days is $34.70.

(a) How many coins were there altogether?

(b) How many of the coins were 20-cent coins?

Need help to solve above questions. Thanks!