Answer:
x = 13
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Summing the 3 given angles and equating to 180 gives
7x + 10 + 4x + 17 + x - 3 = 180
12x + 24 = 180 ( subtract 24 from both sides )
12x = 156 ( divide both sides by 12 )
x = 13
