ok so im in a band we got some chord sequences, and we would like to play a harmonized solo bit over the top

the little sequence is as follows, its is a moderlatey slow pace

e---------------------------------------- ( DROP D )
b--------------------------------- ---
g- 7777---------3333--5555---
d- 7777- 3333-3333- 5555--------- and so on
a- 5555- 3333-1111--3333-------

what i would like to know is how i work out what key this is in

then once i know the key i need a scale. once i have the scale i can harmonize perfectly fine

and if its major or minor will help i know a few scales but i need a help finding key and a okay scale

Cheers guys
Looks like F and it's ambiguous, meaning you could go either major or minor. I'm no expert, though, so let's see what others have to say.
It's in D minor the way you have it written out (assuming it just repeats that progression after that).

D E F G A Bb C
1 2 b3 4 5 b6 b7

D5 F5 Bb5 C5
*Washed up response from many other threads*

Look at the music and see what notes are sharp/flat.

Assign the song a major or minor key by using your understanding of the Circle of Fifths. (For example: If you have F# and C# in the piece instead of F natural and C natural, looking at the circle of fifths you can tell that that is either the key of D major or B minor)

Then you have to find the tonal center. (In my example of D major or B minor: You would see if the music wants to resolve on a D major chord or a B minor chord. You know it sounds resolved when it sounds complete or finished.)

Whatever note it wants to go to either X major or Y minor is the key. [In my example: If it wants to end on a D major chord, it's in D major (that's taking into account the sharp notes, NOT just the fact it wants to end on D major.)]

If you don't have an understanding of the Circle of Fifths, read this thread in which Casualty01 (Chris aka Cas) has an amazing post: https://www.ultimate-guitar.com/forum/showthread.php?t=14696&highlight=circle+of+fifths
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