a: Xét tứ giác MNPQ có
\(\widehat{M}+\widehat{N}+\widehat{P}+\widehat{Q}=360^0\)
=>\(x+80^0+110^0+120^0=360^0\)
=>\(x=50^0\)
b: Xét tứ giác EHGF có
\(\widehat{E}+\widehat{H}+\widehat{G}+\widehat{F}=90^0\)
=>\(x+90^0+90^0+90^0=360^0\)
=>\(x=90^0\)
c: Xét tứ giác ABCD có
\(\widehat{A}+\widehat{B}+\widehat{C}+\widehat{D}=360^0\)
=>\(x+90^0+90^0+65^0=360^0\)
=>\(x=115^0\)