Is it a acute, a right, a obtuse triangle and either a scalene, a isosceles or a equilateral triangle?

Equilateral triangle

Step-by-step explanation:

When all the sides are the same or equivalent in a triangle, the triangle is called an equilateral triangle.

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.