6+ y = -2 can someone tell me the answer and explain it to me

How can we find the measure of an exterior angle if we know the measurement of an interior angle

Noor brought 21 sheets of stickers. she gave 1/3 of a sheet to each of the 45 students at recess. she wants to give teachers 1 1/2 sheets each.

Asystem of equations has 1 solution. if 4x-y=5 is one of the equations , which could be the other equation ?