hey i dont know much about theory but can someone please answer this for me without getting to complicated? If i was gonna right a solo and lets say it's in 4/4 time and say the rythmn is an e5, g5, and a5 for example and the rythmn goes 1 2 3 4 then switch powerchord and so on how do i know what scales i could use to solo in? Please help without making me feel stupid thanks ug i appreciate it.
you could solo over every "chord",by just following it.. arpeggios and stuff..
the fact that`s it`s a power chord,allows you to follow it either it was minor or major.
the second way around,is to analyze your progression,and find out in what key is it.
by e5,g5,a5,you could use the E minor pentatonic scale.. assumin e is the tonic,g and a are a part of this scale..
Look at the notes that make up the chords, and use a scale that has those notes.

In your case
E5 - E B
G5 - G D
A5 - A E

That's E minor pentatonic

You could also use E minor (It has all those notes as well)
My name is Andy
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First, think about where the chords resolve. Play them and listen where is the tension and where is the resolve. Which chord is the stable chord. I would think E in this case. So it will be a scale with some kind of E root.

Next write down all the notes being played in the progression.

E5 = E B
G5 = G D
A5 = A E

Then arrange them in order...
So we are looking for a scale that uses E G A B D
Instantly we have
E minor pentatonic scale = E G A B D
step pattern = W+H - W - W - W+H - W

Or we could flesh it out a bit for a full diatonic scale to play with adding a little more colour about the place.

If we want to get a full diatonic scale we look for where the half steps are. This will be a big clue as to whether we need to sharp or flat a note to get a diatonic scale that follows the pattern of the major scale or one of it's modes.

We know we are missing some kind of F and some kind of C in this scale and because there are no half steps already present we can use the F and C to complete the scale in a couple of different ways.

We could add an F# and C to get
E minor = E F# G A B C D E (Relative to the G major scale)
Step Pattern = W H W W H W W (Aeolian mode)

or we could add F# and C# to get
E Dorian = E F# G A B C# D (Relative to D major scale)
Step Pattern = W H W W W H W

or we could add F and C to get
E Phrygian = E F G A B C D E(Relative to C major scale)
Step Pattern = H W W W H W W

Adding F and C# would create a step pattern that does not fit the major scale pattern or any of it's modes since there will be four whole steps in a row. H W W W W H W
This would actually be the first mode of the Melodic Minor scale
E F G A B C# D E (Relative to D Melodic Minor Scale) I don't know what this scale would be called but there you go. I know - too complicated, sorry I just can't help myself.