What does it mean if a line is perpendicular to another line?

How many credit hours will a student have to take for the two tuition costs to be equal? round the answer to the nearest tenth of an hour.

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 (monthly car loan payment per $1,000 borrowed) i need !

Can someone me do math because i am having a breakdown rn because i don’t get it