Well, if we know that a and b are parallel, that means they have the same slope but different y-intercept. So, if c and a intersects, then c and b are bound to intercept, because when c intersects with a, it will also cross b, since it will be going in the same route...which will make it also intersect with b. (crossing.)
she has 4 friends to spend the 100 dollars on because she wants to spend the same amount on each friend you can multiply 4x. you can't spend more than 100 but you can spend 100$ so it would be <=100
