200 times what equals 20

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?

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9

Factor this polynomial completely. x^2-8x+12