Question

how to do it please show me

Answer 1

∠a+∠b=180° (linear pair)
∠a-∠2b=30° (given)
 THEN SUBSTITUTE IT
we will get 3b=150°
then b=150/3=50
then put the value of b in first equation
a+50=180
a= 180-50=130

Answer 2

acording linear pair
a-2b=30
a=30+2b
a\q
30+2b+b=180
30+3b=180
3b=180-30
b=150\3
b=50
therfore
a=30+2b
a=30+2×50
a=30+100
a=130