5x+10y=40(5.50)

You cannot really 'solve' it because there are an infinite number of solutions.  

5x+10y=220

5x + 10y =40(5.50)

x  + 2y   = 8(5.50)

x  + 2y   = 44.00

x  + 2y - 44 =0

we can set this as y= mx +c

so,

x+ 2y =44

2y = -x -44

y   =-1/2x -44

Now we can draw a graph that formula. and we can solve this formula