In a quadrilateral angles are in the ratio $2:3:5:8$ then the smallest angle is 

$\begin{array}{l}\angle A:\angle B:\angle C:\angle D=2:3:5:8\\ \angle A=2x,\angle B=3x,\angle C=5x,\angle D=8x\\ \angle A+\angle B+\angle C+\angle D=360°\\ 2x+3x+4x+8x=360°\\ 18x=360°\\ x=\frac{360°}{18}=20°\\ x=20°\\ \angle A=2\times 20°=40°\\ \angle B=3\times 20°=60°\\ \angle C=5\times 20°=100°\\ \angle D=8\times 20°=160°\end{array}$