Question 48492
1st, get the value of x by transposing the y to the left side 
x^2=20-y^2   then substitute to the y of the 2nd equation
20-y^2-2y^2=8  >>>>   -3y^2=-12    
                      ----   ---    =   y^2= 4 >>  y=2
                       -3    -3