Take the totally needed to buy it, put the amount you have and then add but substitute for a variable the amount needed.
The slope of this line is -1 because it goes down one and to the right one
There is a 50%, or 1/2, chance of getting heads on each flip. Each of the 500 trials is independent. Because there is a 1/2 chance of getting heads, you would expect half of them to land on heads. 500/2 = 250. You would theoretically expect 250 heads if you tossed an unbiased coin 500 times.
First what you need to do is distribute the properties. Take 2x times the -3 and you will get -1x. Then take the 12 and times it time x and you will get -12x, and then times 12 times 1 which is 12, now here's a fact so you don't get confused, instead of the plus and minus signs it's a negative and positive signs) then you take -1x and -12x and divide them by each other and you will get 12, X=12
