This is for a test so i need it fast plz help (picture attached)

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Lee has $1.75 in dimes and nickels. the number of nickels is 11 more than the number of dimes. how many of each coin does he have?

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years