given that3m -9n =24when n= -1substitute it in the equationthus3m -9(-1)=24solving for m3m +9 =243m =24-93m=15dividing through by 33m/3 =15/3m =5 . thus when n= -1 , m=5also put n=1 into the equation3m -9(1) =243m -9 =24 3m= 24+93m =33dividing through by 33m/3 = 33/3m=11thus when n= 1, m=11lastly, put n= 3 into the equation3m -9(3) =243m -27 = 243m = 24+273m =51dividing through by 33m/3 =51/3m =17. Thus when n = 3 , m= 17.