8:-
[tex]\\ \sf \longmapsto 5x+20=40[/tex]
[tex]\\ \sf \longmapsto 5x=40-20[/tex]
[tex]\\ \sf \longmapsto 5x=20[/tex]
[tex]\\ \sf \longmapsto x=\dfrac{20}{5}[/tex]
[tex]\\ \sf \longmapsto x=4[/tex]
9:-
As its a isosceles triangle
[tex]\\ \sf \longmapsto x+y+60=180[/tex]
[tex]\\ \sf \longmapsto 2x+60=180[/tex]
[tex]\\ \sf \longmapsto 2x=120[/tex]
[tex]\\ \sf \longmapsto x=y=60[/tex]
and
[tex]\\ \sf \longmapsto z=x+60÷60+60=120[/tex]
