Find an expression for the number of colored border tiles needed for any N x N square center.

8N - 4 border tiles.

Step-by-step explanation:

There are 4 border tiles in each corner and between  the tiles there are N-2 tiles along the 4 sides.

So the number of border tiles

= 4+ 4(N - 2)

= 4 + 4N - 8

= 8N - 4.

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.

its totaly b

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