What does c equal when the equation is 19-4c=17

What are the exclude value of mn+3m

You dug a hole that was 8 feet deep. after taking a short break, you dug down 3 more feet in the same hole. when finished digging, a tractor accidentally filled the hole with 4 feet of dirt. how deep is your hole now?

Find the area of the region that is inside r=3cos(theta) and outside r=2-cos(theta). sketch the curves.