Answer:
a) x = 10
b) x = -40
c) x = 10, -40
Explanation:
a)

Taking 10 to the right hand side 10 becomes positive

So x = 10
b)

Taking 20 to the right hand side 20 becomes negative

Multiplying both sides by 2

So, x = -40
c)

Hence, x = 10, -40
So, two solutions can be provided