Answer:
solving the given equation,
x-3.1y=11.5
-x+3.5y=-13.5
----------------------
0.4y= -2.5
or, y= -2.5÷0.4
or, y= -6.25
put the value of y in first eqn
x-3.1×(-6.25)=11.5
or, x+ 19.375=11.5
or, x= 11.5-19.375
or, x = -7.875
therefore x = -7.875 and y= -6.25ans.
