Question

(3) Let the angle be ( x^{circ} )
1. Then, it's supplementary angle ( =left(180^{circ}-xright) ) According to the question,
( begin{array}{rr} & x-left(180^{circ}-xright)=20^{circ} Rightarrow & 2 x-180^{circ}=20^{circ} Rightarrow & 2 x=200 x=100^{circ}end{array} )

# 1. An angle is greater than it's supplementary angle by 20°. Find the angle. (1) 80 (2) 90° (3) 100° (4) 120°

Solution