What's the answer to all of these questions?

Identify an equation in point slope form for the line perpendicular to y=3x+5 that passes through (4,-1)

Don't know how to find x given these segment lengths

Mr. and mrs. wallace have decided to buy a car for $21,600. they finance $15,000 of it with a 5-year auto loan at 2.9% arp. what will be their monthly payment be? a. $268.20 b. $268.86 c. $269.54 d. $387.16 i need !