Which mathematical operation is indicated by the phrase broken up into

The mathematical operation indicated by the phrase 'broken up into' is division. And if you think about it, it makes sense since the definition of division is 'breaking something apart'.
Hope that helped =)

So we know that  isosceles triangles have 2 sides of equal lengths and a third side. also, two angles are equal with the third is not. since the sides meet at an angle of 40, we know that the missing angle must be 180 - 40 - 40 = 100 degrees.we also know one side (c) = 18 inches. so since we have an angle of 100 degrees across from a side length (18), we can find the other side lengths (a and b)a/sina = b/sinb = c/sinc    (a/b/c are sides, a/b/c are angles)18/sin100 = b/sin40 so b=11.7 inches so a is also a=11.7 inches