Can I please get help I don’t really understand

The system of equations graphed below has how many solutions?

Julius sold five times as many computers as sam sold last year. in total, they sold 78 computers. how many computers did julius sell?

Abag contains 4 red, 7 blue and 5 yellow marbles. event a is defined as drawing a yellow marble on the first draw and event b is defined as drawing a blue marble on the second draw. if two marbles are drawn from the bag, one after the other and not replaced, what is p(b|a) expressed in simplest form? a. 7/16 b. 7/15 c. 14/16 d. 14/15