Can some one give me a step by step with all the work and answer 8n + 7 = 31

I presume you're trying to find n, so first remove the 7 from each side.

8n + 7 -7 = 31-7
=> 8n = 24
Then divide both sides by 8, as you want only n

8n/8 = 24/8
n = 3

Well we are trying to isolate n to be alone. 
So lets solve our equation step by step 

first! subtract 7 from both sides
8n + 7 = 31 
       -7 = -7 it cancels out on the left hand side and you solve for the right. 

second! now lets set up our equation once again 
8n = 24 

Third! Now we divide both sides by 8 to isolate n to be alone. 
8n = 24 
÷8 = ÷8 and the left side has n alone and 24 ÷ 8 = 3 s...

fourth! lets set up what we have left 
n = 3 

So our answer is finally
n = 3 

love, the Pineapple. 
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