Find the intervals on which f(x)=2xx2+64 increases.

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?

I'm confused on this could anyone me and show me what i need to do to solve it.

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.