Look at the picture I need help

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line

Witch represents the inverse of the function f(x)=1/4x-12

Aschool allots ? 1500 to spend on a trip to the theatre. theatre tickets have a regular cost of ? 55 each and are on offer for 1 5 off. a train ticket for the day will cost ? 12 each. if 2 teachers and the maximum number of students attend, how much money will the school have left over?