Does anyone know the answer?

d = 9

Step-by-step explanation:

Calculate the slope m using the slope formula and equate to 3

m =

with (x₁, y₁ ) = (4, 6) and (x₂, y₂ ) = (d, 21)

m = , that is

= 3 ← multiply both sides by d - 4

15 = 3(d - 4)

15 = 3d - 12 ( add 12 to both sides )

27 = 3d ( divide both sides by 3 )

9 = d , that is

d = 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.