Answer: 56 degrees
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Work Shown:
For any triangle, the three interior angles always add to 180
(4x-12) + (6x-17) + (2x+5) = 180
(4x+6x+2x) + (-12-17+5) = 180
12x - 24 = 180
12x = 180+24 ..... adding 24 to both sides
12x = 204
x = 204/12 ..... dividing both sides by 12
x = 17
We can use this x value to find the three angles
4x-12 = 4*17-12 = 56
6x-17 = 6*17-17 = 85
2x+5 = 2*17+5 = 39
As a check,
56+85+39 = 180
which confirms we have the right x value.
We see that 56 is the middle angle, so this is the second largest angle.