If bert had 3 cents more he would have twice as much
as georgia. if he had 4 cents less, he would
have the same amount.
how many cents does bert have?

Let x be the number of coins bert had 
let y be the number of coins georgia has 

x+3 =2y equation 1 
x-4 = y equation 2 

now, since y=x-4, you can put that in the first equation 

it becomes x+3= 2(x-4) right because y is the same thing as x but you can't solve for 2 letters so we have to make them the same. 

so your new equation is x+3 = 2(x-4) 

expand so you get x+3= 2x -8 
then solve for x by putting the x's on one side and the numbers on the other 

bring x over --- 3= 2x- 8 - x and subtract the xs to get 3= x-8 

then bring the 8 to the other side 
3+ 8 = x 
x= 11 
note: remember! when you're bringing numbers and letters to the other side, you have to reverse the operation: say you have x+1 = 2 --- when bringing the one over to the other side it becomes a -1 x+1= 2-1 

so bert has 11 cents. 
this question is a little difficult, it takes some practice and it's stuff you'll learn in high school so don't worry too much if you don't get it