x+3y=-1 Multiply 3 to each side x*3+3y*3=-1*3 3x+9y=-3 Use substitute property 3x+9y=-3 - 3x+y=17 = 8y=-20 Divided 8 to each side 8y/8=-20/8 y=-2.5
3x+y=17 Substitute y with -2.5 3x+(-2.5)=17 3x-2.5=17 Add 2.5 to each side 3x-2.5+2.5=17+2.5 3x=19.5 Divided 3 to each side 3x/3=19.5/3 x=6.5 Next, 3x+3y Substitute x with 6.5 and y with -2.5 3(6.5)+3(-2.5) =19.5-7.5 =12 is your final answer. Hope it help!