Answer: Angle A is 55 degrees.
Explanation:
The sum of a triangle's angles must be 180 degrees.
That means: 79 + (6x+4) +(6x+13) = 180
Add the like terms to get: 12x + 96 = 180
Subtract 96 from both sides: 12x = 84
Divide both sides by 12: x = 7
Now that we know x = 7, we can substitute that into 6x + 13 to find Angle A.
Angle A = 6(7) + 13 = 42 + 13 = 55 degrees