These are both standard algebra rearrangements.

Start from:

(multiply both sides by CP)

The CP on the right hand side cancels (its on the top and bottom of the fraction

(Divide both sides by 10)

Expand Brackets(this gives step 3)

Add 10CP to both sides

CancelThis gives step 4

This is because:

10CP + 3CP = 13CP

-10CP + 10CP =0CP =0