math very hard :/

Question

X=3

3x-12y=45 pls help me do this

Answer 1

Okay, Joe.

So they have given you 2 equations.

The first equation listed is simply telling you the value of x: X = 3

The second equation is where all of the math is involved.

You have the equation: 3x - 12y = 45

Since it is given that x = 3, we will plug that number "3" in for x, like this:

3(3) - 12y = 45

9 - 12y = 45

-Now, we will solve for "y" by performing the INVERSE OPERATIONS (or the opposite operations).

We want to get y all by itself on one side of the "=" to find out its value. So we need to move anything else to the other side of the equals sign.

We will start by moving the 9 to the right side of the "=". Since it is a positive 9, we will subtract 9 from the left side of the equation to get rid of that 9 and in order to keep everything balanced/equal, we will need to also subtract 9 from the right side. Like this:

9 - 12y = 45

-9 -9

-12y = 36

Now all we need to get rid of is the -12 in order to have y all by itself on the left side of the "=".

-12y means that we are multiplying y by -12, so to get rid of the negative 12, we need to divide both sides by -12, like this:

-12y = 36

¯¯¯ ¯¯¯

-12 -12

y = -3

Now we know the values for both x and for y that make this equation true:

X = 3 and Y = -3

Answer 2

x = 3

3x - 12y = 45

since x = 3, we can substitute 3 for x in 2nd equation and solve for y:

3(3) - 12y = 45

9 - 12y = 45

-12y = 36

y = -3