Please help. thank you

Hi!

So, first, let's just form the equation:

We know that all the side lengths equal 12 cm.

So the equation will be:

5 + 3 + x = 12

The answer you put in the box is:

5 + 3 + x

To find the value of x, we just solve this equation:

5 + 3 + x = 12

Combine like terms:

8 + x = 12

Same to both sides:

x = 12 - 8

x = 4

I hope this helped, let me know if you have any questions.

all the angles opposite to the angle 150 would be 150 and all the angles that are next to 150 are 30 because they equal 180 it you add it up.

step-by-step explanation: