#### Answer

(a) $72^{\circ}$
(b) $60^{\circ}$

#### Work Step by Step

(a) We can find the angle between two consecutive blades:
$\frac{360^{\circ}}{5} = 72^{\circ}$
(b) We can find the angle between two consecutive blades:
$\frac{360^{\circ}}{6} = 60^{\circ}$