15 decreased by twice a number algebraic expression?

Fiona joins a fruit of the month club. the entry cost was $25 and then she pays $18 per month. if she participates for 8 months, how much will she pay in all? how much in 10 months?

If you flip a coin 3 times, what is the probability of flipping heads 3 times? a. p(3 heads) = 3/8 b. p(3 heads) = 1/6 c. p(3 heads) = 1/8 d. p(3 heads) = 1/2

What adds to be the bottom number but also multiplies to be the top number with 8 on the bottom and 15 on top