Could someone me on 6 7 and 8? so

7. We know that they must all add up together to get 90 degrees because of the symbol show the right angle. 
We can use this to form and solve an equation:
2x +1x + 30 = 90
3x+30 = 90  (add the x's together)
3x = 60    (subtract both sides by 30 to get the x's alone)
x =20  (divide by 3 to get what 1x is equal to)

(The next question is very similar)
8. To solve this, we need to know what all the x's together are equal to.
Since angles on a straight line add up to 180 degrees -we can make an equation:
4x+x+30 = 180 
5x + 30 +180  (add all the x's together)
5x = 150  (subtract both sides by 30 to get what 5x is equal to)
x = 30 (divide by 5 to get what just 1x is)

Hoped this helped - please ask if anything doesn't make sense!