Twelve and nine thousandths
Step-by-step explanation:
1.) Plug in one of the points.
y = 8x + b
6 = 8(4) + b
2.) Solve for b (or [?])

32 cancels out on the right side.
Subtract 32 from 6, which is -26
3.) -26 = b
4.) Check with other point:
-2 = 8(3) + b
-2 = 24 + b
Cancel out 24 on the right side: 24-24 = 0
-2 - 24 = -26
-26 = b
NOT NECESSARILY would a triangle be equilateral if one of its angles is 60 degrees. To be an equilateral triangle (a triangle in which all 3 sides have the same length), all 3 angles of the triangle would have to be 60°-angles; however, the triangle could be a 30°-60°-90° right triangle in which the side opposite the 30 degree angle is one-half as long as the hypotenuse, and the length of the side opposite the 60 degree angle is √3/2 as long as the hypotenuse. Another of possibly many examples would be a triangle with angles of 60°, 40°, and 80° which has opposite sides of lengths 2, 1.4845 (rounded to 4 decimal places), and 2.2743 (rounded to 4 decimal places), respectively, the last two of which were determined by using the Law of Sines: "In any triangle ABC, having sides of length a, b, and c, the following relationships are true: a/sin A = b/sin B = c/sin C."¹