In the triangle beside, what is the value of X?
A
35 degree
B
40 degree
C
45 degree
D
60 degree
Correct Answer: 35 degree
<math xmlns = "http://www.w3.org/1998/Math/MathML"><mn>4</mn><mi>x</mi><mo> + </mo><mn>40</mn><mo>°</mo><mo> = </mo><mn>180</mn><mo>°</mo></math><math xmlns = "http://www.w3.org/1998/Math/MathML"><mo>⇒</mo></math> = <math xmlns = "http://www.w3.org/1998/Math/MathML"><mn>180</mn><mo>°</mo></math><math xmlns = "http://www.w3.org/1998/Math/MathML"><mo>⇒</mo></math> x = <math xmlns = "http://www.w3.org/1998/Math/MathML"><mn>35</mn><mo>°</mo></math>