Can someone me understand how to solve a two variable equation i am really lost

Easiest method solving 2 unknowns is Substitution. 
So there will normally be 2(ormore)equations given. 
Say 
X+Y= a
 bX=cY + d 
a b c d are numbers they give
So first we rearrange the first equation
X  = a - Y 
No we substitute this into the 2nd equation so that we can get Y
since we know X = a-Y, 
b(a-Y) = cY + d 
we rearrange and we can find Y for this, it is just Y and numbers
hence finding Y, we sub the value for Y into X = a-Y and we get X also .