What is the value of x? ____° b= 70 and a=30 c=x

Are you talking about a triangle?If so, the angles in a triangle add up to 180.70 + 30 = 100So c must be 80 because 100 + 80 = 180.x = 80

A + B + C = 180
30 + 70 + X =180
100 + X =180
X =180 - 100
X =80.