For number 20:
Because a triangle is 180 degrees, we will equal all the angles we know to that. So, this is how we will write our equation:
Solve for x:
60 + x + 20 + 3x = 180
4x = 100
x = 20
Using 75, you can find the angle measure by plugging 75 where x is present in the angle measures. For example:
x = 20,
20 + 20 = 40
3(20) = 60
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For number 21:
The shape shown is basically two triangles, so 180 x 2 is 360. Again, same procedure. Add all known angle measures and make an equation where they all equal 360.
Solve for x:
x-5+x+35+1.4x+x=360
x = 75
By isolating x, you should get an answer of 75. Now, plug that into each of the equations:
x = 75
75 + 35 = 110
75 - 5 = 70
1.4(75) = 105
