its pretty simple really, you have to find b to begin
p.s. you don't need to worry about 8c+5d, that's just there to confuse you.
these to angles : (12b+6)° and (2b+6)° if added together have to equal 180°
so you add the two equations together
(12b+6)+(2b+6)=180
you then solve for b:
add like terms together
12b+2b and 6+6
you then are left with
14b+12=180
then you solve for x
14b+12=180
-12 -12
14b=168
÷14 ÷14
b=12
now that you have B you
plug that in to the original equation opposite of (4a)
(2b+6)
you plug in the number you got for b
2(12)+6
24+6
=30
so now you now the angle opposite of (4a)
and opposite angles have to equal each other so
4a=30
solve for a and that's your answer
4a=30
÷4. ÷4
a=7.5
