I need help with both problems, one is also fine. Please help, this is matrices algebra.

Asmall foreign car gete 42 miles per gallon and user 35 gallons on a trip.gasoline costs $1.05 per gallon.what was the cost of gasoline per mile driver?

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

You and a friend went to the movies.you spent half your money on tickets. then you spent 1/4 of the money on popcorn, $2 on candy, and $3 on a soda. if you have $1 left, hiw much money did u take to the movies?