NewMovies charge $4 each month to use their DVD rental service and $2.25 per DVD rental. Trya's bill month was $31. How many DVD's did she rent last month

Step-by-step explanation:

Let's look at a few examples where we know the number of movies. Let's say just 1 movie is rented. Well, then there's the subscription charge of 4 dollars and then 2.25 for the one movie. Two movies would be 4+2.25+2.25. 3 would be 4+2.25+2.25+2.25. So the number of 2.25s increases with each movie. You could brute force it and just keep adding 2.25 until you get 31, but there's a better way.

Multiple additions like this is of course multiplication. so one movie is 1*2.25, two is 2*2.25 and so onwe want to know how many were bought, so let's call that number something we don't know, x. Also, you want to take into account the 4 dollar subscription fee. This leaves us with an equation that looks like this.

4+2.25x = 31

Now, to solve for x we can do a few things to this. I'm assuming you are new to this so I will take it slow. Let's say it was a simpler problem. 5+x=10. Or five plus something equals 10. You might be able to figure it out super easily and just know that 5+5 is 10. A way to solve it with our problem though is to take the euations 5+x=10 and manipulate it on each side of the equation. Here, 5 is being added to x, but what if we subtract 5? well, 5+x-5=x. Since we did that to one side of the equation though we have to do the ame to the other side. so 10-5. Or in other words we subtracte 5 from both sides.

5+x=10

-5 - 5

x = 5

So that's ne part of how we are going to find x in 4+2.25x = 31

4+2.25x = 31

-4 - 4

2.25x = 27

Now, in the last part 5 was being added so we subtracted. Here, 2.25 is being multiplied so we divide. If we divide both sides by 2.25 we get x = 12, so that's the answer.