Question

What is 0.5x+ 2.2y=9

Answer 1

What you can do is multiply the whole first equation by 12, so 6x + 26.4y = 108.
then since the coefficients of the x value (the number in front of the x) are the same in both equations, you can subtract the second equation from the first:
  6x + 26.4y = 108 
-(6x +  0.4y  = -22) 
            26y  = 130   divide by 26
                y  =  5
you can then plug y=5 into one of the equations to solve for x:
0.5x + 2.2(5) = 9
0.5x + 11 = 9 subtract 11 from both sides
0.5x = -2    multiply each side by 2
x = -4