Answer:
a.
2x+4x+3x=180 sum of interior angle of the triangle is 180
9x=180
x=180/9=20
b.
x-20+x+10+x-20=180sum of interior angle of the triangle is 180
3x-30=180
3x=180+30
x=210/3=70
c.x+10+x+20+x=180 linear pair
3x+30=180
3x=180-30
x=150/3=50
42-25=17. So Rodney has 17 stickers. :)
2(x-8)=7
Distribute on the left side
2x-16=7
Add 16 to both sides
2x=23
Divide both sides by 2
x=11.5
Final answer: The number is 11.5
There are 4 terms in the expression ^_^