In a quadrilateral, the angles are $x°,\left(x+10\right)°,\left(x+20\right)°$ and$\left(x+30\right)°$ , then the measure of greatest angle is

$x°+\left(x+10\right)°+\left(x+20\right)°+\left(x+30\right)°=360°$

$\Rightarrow 4x°+60°=360°$

$\Rightarrow 4x°=360°-60°$

$\Rightarrow 4x°=300°$

$\Rightarrow x°=75°$

$\left(x+10\right)°=75°+10°=85°$

$\left(x+20\right)°=75°+20°=95°$

$\left(x+30\right)°=75°+30°=105°$

The greatest angle is $105°$