1. since the equations equal each other 2x+19=x+7 -x -x x+19=7 -19 -19 x= -12 sub into y= x+7 y= -12+7 y= -5
2. x+2y=-7 <span>x+y+23=0 i don't know what the second equation is equal to, i'll assume 0
2y=x-7 y=1/2x-7/2 sub this into x+y+23=0 x+1/2x-7/2+23=0 3/2x+39/2=0 -39/2 -39/2 3/2x= -39/2 x=-39/2 / 3/2 x= -13 sub into y=1/2x-7/2 y=1/2(-13)-7/2 y= -10
3. </span>x+5y=2 <span>x=-4y+5 </span>sub x=-4y+5 into x+5y=2 -4y+5+5y=2 y+5=2 -5 -5 y= -3 sub y =-3 into x =-4y+5 x=-4(-3)+5 x= 17
4. 3x+y=9 <span>y=-5x+9 </span>sub -5x+9 into 3x+y=9 3x+(-5x+9)=9 3x-5x+9=9 -2x+9=9 -9 -9 -2x=0 x=0 sub into y=-5x+9 y=-5(0)+9 y=9
