In order to do this you have to substitute b with 9 and get 3a+9=54, now subtract 9 from both sides to leave a by itself and get 3a=45, now divide 3 in both sides to leave a by itself and get a=15
Yes she do break even because let me show you a expression now take a number line and then you start at -16 right and then you go down the number line and then this is how it go -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 and i just answer your Q there you go -16+16=0