a. To write an expression for the number of points you earn from the coins, you need to consider that each coin you collect is worth 10 points. Therefore, the number of coins you collect can be denoted by "c".
The expression for the number of points you earn from the coins is: 10c.
b. To write and simplify an expression for the total number of points you earn, you need to take into account the star you found that triples your score.
Since the score from the coins is represented by 10c, multiplying it by 3 (due to the triple effect of the star) gives you the expression for the total number of points: 3(10c).
To simplify this expression, you can distribute the multiplication by 3: 3 * 10 * c.
This simplifies to: 30c, which represents the total number of points you earn.