Question

What is the value of x

Answer 1

x = 21°

Explanation:

Total degrees in a triangle = 180°

180° - 100° = 80°

x° - 4 + 3x° = 80°

Combine x values together:

4x° - 4 = 80°

Add 4 to each side:

4x° = 84°

Divide 4 from each side:

x° = 84°/4° = 21°

Check your work:

21 - 4 + 3(21) = 80°

x = 21°

Answer 2

21°

Explanation:

Since the interior angles of a triangle always add up to 180°, and you already know that one angle is 100°, you know that the sum of the remaining two angles is 80°. Therefore, you can set up an equation:

x° - 4 + 3x° = 80

x° + 3x° = 84

4x° = 84

x° = 21°