Step-by-step explanation:
1)3x+21=6x-60
81=3x
x=27
3 times 27-21
=81-21
=60
Equation:3x+21=6x-60
Value of x:27
Angle measures:60 & 60
2)12x-18=8x+10
4x=28
x=7
12 times 7-18
=84-18
=66
Equation:12x-18=8x+10
Value of x:7
Angle measures:66 & 66
3)7x+9+5x+3=180
12x+12=180
12x=168
x=14
7 times 14+9
=98+9
=107
5 times 14+3
=70+3
=73
Equation:7x+9+5x+3=180
Value of x:14
Angle measures:107 & 73
4)3x+10+3x-28=180
6x-18=180
6x=198
x=33
3 times 33+10
=99+10
=109
3 times 33-28
=99-28
=71
Equation: 3x+10+3x-28=180
Value of x: 33
Angle measures:109 & 71
5)12x+15=15x
15=3x
x=5
15 times 5
=75
Equation:12x+15=15x
Value of x:5
Angle measures:75 & 75
Hope I helped!!!
