The least common multiple (LCM) is the smallest positive integer that is a multiple of two or more integers.

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

2 + (4 + 3) ÷ 5 x 3 - 4²
P: 2 + (7) ÷ 5 x 3 - 4²
E: 2 + 7 ÷ 5 x 3 - 16
MD: 2 + \( \frac{7}{5} \) x 3 - 16
MD: 2 + \( \frac{21}{5} \) - 16
AS: \( \frac{10}{5} \) + \( \frac{21}{5} \) - 16
AS: \( \frac{31}{5} \) - 16
AS: \( \frac{31 - 80}{5} \)
\( \frac{-49}{5} \)
-9\(\frac{4}{5}\)

To simplify this fraction, first find the greatest common factor between them. The factors of 16 are [1, 2, 4, 8, 16] and the factors of 60 are [1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60]. They share 3 factors [1, 2, 4] making 4 their greatest common factor (GCF).

Next, divide both numerator and denominator by the GCF:

\( \frac{16}{60} \) = \( \frac{\frac{16}{4}}{\frac{60}{4}} \) = \( \frac{4}{15} \)

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

-9b³ - 4b³
(-9 - 4)b³
-13b³

The greatest common factor (GCF) is the greatest factor that divides two integers.