Question 146874
Wow, you spent a lot of time typing in all 24 of those problems and answers. 
I'm a little concerned that you're taking a survey of your algebra knowledge and you don't understand any of it. 
I'll help you with 3 problems. 
You may want to consider that algebra.com may not be the best way to help yourself in this case.

1. Percentage and decimal
2.8% is the same as 2.8/100. 
2.8/100=0.028

2. Percent means out of 100. Set up a proportion.
{{{168/480=x/100}}}
Solve for x.
{{{x=100(168/480)}}}
{{{x=35}}}
168 is 35% of 480. 

3. 2x(3x - 4y) – 3x(-3x + 4y)
Use the distributive property. 
{{{2x(3x-4y)-3x(-3x+4y)=2x(3x)-2x(4y)-3x(-3x)-3x(4y)}}}
{{{2x(3x-4y)-3x(-3x+4y)=6x^2-8xy+9x^2-12xy}}}
{{{2x(3x-4y)-3x(-3x+4y)=15x^2-20xy}}}

Good luck.