What is 2a + 4 = 10 "solve the equation"

Here is how to solve your equation: 
You have to subtract 4 by both sides. How do we know to do this? Well, there is a positive 4 standing on it's own, you need to subtract a negative 4 with positive 4 and 10, like this:
2a+4-4=10-4
The, "+4-4" part should be canceled out, you shouldn't continue on that part. "10-4" equals 6, so here is how your equation should look: 
2a=6
Now it's time for you to divide 2 on both sides. How do we know to divide 2 by both sides? Well, you have to get the variable by itself, so the number with the variable must be divided in order to get your answer. So this is how your problem should look now: 

Cancel out the  and divide 
After you've divided  your answer shall be: 


I hope this helps, good luck with your studies~!