simplify both sides  -23=-2a+10+a -23=(-2a+2a)+(10) <-- combine like terms -23=-a+-10 -23= -a -10 Flip the equation -a -10=-23 add 10 to both sides -a -10(+10) =-23(+10) -a=-13 divide both sides by -1 -a/-1=-13/-1 answer a=13  Hope this helped :))