Given ABCD slove for X ?

∠D = 180°- ∠A

∠D = 180° - (30+5x)

15+10x = 180° - 30-5x

15x = 180 - 30 - 15

15x= 135

x = 9

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.