Subject: Question Name: Vijai Who are you: Student (All) If 5x+4y=6 then x+y=? please answer it with steps involved Hi Vijai. If you are expecting a number as the answer to x+y=? then you will have to think about the question again. For example: if x = 2 and y = -1 then 5x + 4y = 6 and x + y = 1 but if x = 6 and y = -6 then 5x + 4y = 6 and x + y = 0 5x+4y=6 means that the values of x and y depend on each other. If you were to draw a graph of this relationship, you would find that it is a line. For any specific value of x, there is a corresponding value of y, and for any specific value of y, there is a corresponding value of x. So when you ask "what is x+y=?" you can now understand that x and y cannot be just chosen independently and still obey the relationship 5x+4y=6. The best you can do is to solve the first equation for y: 5x + 4y = 6 4y = 6 - 5x y = ( 6 - 5x ) / 4 Now you can replace the y in x+y=? with what y is equal to: x + y = x + (6 - 5x) / 4 = 4x / 4 + (6 - 5x) / 4 = (4x + 6 - 5x) / 4 = ( 6 - x ) / 4 So x + y = (6 - x) / 4. Stephen and Penny