a)

$108-75=108-70-5=38-5=33$

b)

$210-86=210-80-6=130-6=124$ $210-86=210-80-6=130-6=124$

c)

$500:25=20$

d)

$110:11=10$

e)

$7\cdot 12=7\cdot \left(10+2\right)=7\cdot 10+7\cdot 2=70+14=84$

f)

$100\sout{0}:5\sout{0}=100:5=20$

g)

$\left(27+45\right)-\left(93-38\right)=72-55=17$

h)

$\left(111+39\right)-\left(111-39\right)=150-72=78$