What was an employee’s original salary if the employee earns $7.02 per hour after an 8% raise?

Both the red and blue line segments stretch from the center of the circle to a point on the circle. the length of the blue segment is 5. how long is the red line segment?

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

What are the exclude value of mn+3m