These are 3 different questions. if you answer can u explain so it can help me please.

Step-by-step explanation:

Problem 12:

I think that (2x-y)+60=(2x+y)+40

Because of the Alternate Interior Angles theorem, which places the 40 next to (2x+y) so then you know they are a linear pair. Same can be done for the side with the 60 degree angle. So both sides add up to 180 so they are congruent themselves and you can put them in this format:

(2x-y)+60=(2x+y)+40

         -40             -40

We do this to remove the 40 from the right side completely, and whatever you do to one side of the equation you have to do to the other as well so remove 40 from both.

(2x-y)+20=(2x+y)

-2x             -2x

Again, we are just trying to find out y right now

-y +20=y

+y        +y

20 = 2y

10 = y

Then insert the y into an equation telling us that it is equal to 180 (because we know that from before) to get what x is

(2x-y)+60=180

We can also input our y that we found out was 10 from before:

(2x-10)+60=180

And now we can add up 60 and -10

2x+50=180

Now subtract 50 to both sides

2x=130

And divide both sides by 2

x=75

So x=75 and y=10

Feel free to ask any questions

Problem 13:

The same type of working out, just with different numbers

answer: the value of x is 7cm

step-by-step explanation:

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step-by-step explanation: