Forming and solving equations
will give the branliest and 25 points available

1. 21=a+a+4+2a-3
   4a+1=21
   4a=21-1
   4a=20
   a=20:4=5
2. x+2x+20+7x-10=180
   10x+10=180
   10x=170
    x=170:10=17
3. x+30+2x-60=180
    3x-30=180
    3x=180+30=210
    x=210:3
    x=70
4. 2(2x+3+x-2)=44
    2(3x+1)=44
    3x+1=44:2=22
    3x=22-1=21
    x=21:3
     x=7
5. 48=2(4+x+5)
    x+9=48:2=24
   x=24-9
   x=15
6. 3x+6=5x
    6=5x-3x
    6=2x
    x=6:2
    x=3
7. x+10+2x-40+3x-90=180
   6x-120=180
   6x=120+180=300
   x=300:6=50
   angles are 50+10=60, 2*50-40=60, 3*50-90=60
   the answer is C - equilateral
8. 3x+10=5x-50
   5x-3x=10+50
  2x=60
 x=60:2
   x=30
   the equal sides are 3*30+10=90+10=100
    the other side is x+5=30+5=35
   P=2*100+35=235
10.x+32+2x+40=180
     3x+72=180
     3x=108
     x=108:3=36