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.

a

step-by-step explanation:

i need the pts ignore this answer

hello!

to begin with, we're given that on earth, a rock weighs 20 pounds, and while on jupiter, that same rock weighs 42 pounds. now, we're trying to find the weight of a rock that weighs 10.5 pounds on earth, on jupiter.

to solve this, first, set up a proportion, cross-multiply, and solve it algebraically.

setting up the proportion is the hardest and the most confusing part of the problem, but it's simple.

if on earth, the rock weighs 20 lbs, and on jupiter it weighs 42 lbs, our first part of our proportion is 20/42 lbs. the second part has to be equal to each other. this means that 10.5 has to be on the numerator of the fraction, and x, the value we're trying to find, has to be on the denominator. remember that the rock weighs 10.5 lbs on earth, and we're trying to find the weight of it on jupiter (which is x).

20/42 = 10.5/x

next, you would cross-multiply.

20x = 42(10.5)

20x = 441

now, solve it algebraically by using division.

x = 22.05 lbs

this can be rounded to 22.1 lbs.

therefore, the weight of the rock on jupiter is 22.1 lbs, the fourth choice.