1/4 is the anwers because you need to reduce the fraction
You would need too do 5*5=25 if you did 5*7=35 that would be wrong
This is the isosceles triangle. Therefore, the angles at the base are congruent.
We know that the sum of the measures of the angles in a triangle is 180°.
Therefore we have the equation:

<em>subtract 38 from both sides</em>
<em>divide both sides by 2</em>

<h3>Answer: x = 71.</h3>
Supplementary = 180 degrees...
A + B = 180
3x + 12 + 7x + 38 = 180
10x + 50 = 180
10 x = 130
x = 13
To find the A just substitute x in...
3 ( 13) + 12
A = 51
To check substitute the x..
A + B = 180
3(13) + 12 + 7(13) + 38 = 180
51 + 129 = 180
180 = 180