Teach me! :)

[YeahIknowIdontKnow!]

Hi

Okey i have some problems with basic pretty basic maths. If some one could give me step by step (and even better comment why) for my couple problems that would be pretty sweet.

First one is: 5x + (7x + 2) = 3(2x + 4) - (2x + 2)

im pretty blocked here... i know i should first open the () first,
if its 3(2x plus 4) its: 3x2 plus 3x4 = 6 plus 12 = 18? or im lost right away? lol and if its -( then opened by turning numbers upside down?


Second: Lets say if year 1995 population ZumbaZumba is 19% was under 15years old. Year 2005 population under 15 was 17,3%. How big % chance it was?

How to solve this? and again step by step would be nice with small comments