It works because even if the numbers are broken apart, you are still multiplying the numbers by their values, it's only different because once broken apart, it's in expanded form instead of standard form. It also makes multiplication easier since you don't have to deal with such large numbers.
Yes, it isn’t a fraction, decimal, or mixed number.
Ángulo agudo es aquel que mide menos de 90º
The answer to your question is Y=12
No. There are 3 types of triangles.
Scalene: Triangle which no sides are equal, so all angles aren't congruent
Isosceles: A triangle with 2 equals sides, but has 1 not equal sides.
Equilateral: A triangle which all sides are equal