First Part:
For every parenthesis with a plus sign to its left, you can eliminate the parenthesis (take into account that plus×minus=minus)
a + a - b - a + b
Then you add like terms. This means you add/subtract a with a and same with b and b (I'll organize the terms in alphabetical order but it's not neccesary)
a + a - a - b + b
Since a - a =0 and b - b = 0,
a + 0 + 0
Answer: a
Second part
Since you have a minus to the left of a parenthesis, you have to change the signs of all the terms inside the parenthesis before you eliminate the parenthesis.

Answer: 2a^2
Answer:
Add the two in the middle and multiply it by the outside number
Step-by-step explanation:
But you can’t do that since there’s no like terms as x would be left by itself so you would do 4x times 2 and 3 times 2 which is 8x+6
Answer:
It's y=3x
Step-by-step explanation:
The y-intercept is 0, it's direct variation. The slope(rise/run) is 3.
Coal because but only in last decade as we humans mine and we only have so much of it
Answer:
216°
Step-by-step explanation:
Both chords are the same length, so the left and right arcs are both 72°. The whole circle is 360°, so:
72° + 72° + x = 360°
x = 216°