What is the value of x from the angles

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

Aretha wanted to gather data about the cost of local bowling leagues in her area. she plotted the data and determined that the average bowling league costs consist of a one-time registration fee and a monthly fee modeled by the equation y = 15x + 20. identify and interpret the y-intercept in this model. the y-intercept is 20. this is the cost per month. the y-intercept is 20. this is the cost of registration. the y-intercept is 15. this is the cost of registration. the y-intercept is 15. this is the cost per month.

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.