Question

essas frações não parecem iguais.
12/15 = 16/20

Answer 1

12/15 = (3 x 4)/(3 x 5) = 4/5
16/20 = (4 x 4)/(4 x 5) = 4/5

Portanto, 12/15 = 16/20

Answer 2

Simplifique as duas até que se tornem irredutíveis:

$\dfrac{12_{:3}}{15_{:3}} \to~~~ \dfrac{4}{5}\\\\\\ \dfrac{16_{:4}}{20_{:4}} \to~~~ \dfrac{4}{5}\\\\\\\\ Obtemos ~~o~~mesmo~~resultado,~~logo~~s\~ao~~iguais.\\\\\\ \dfrac{12}{15} = \dfrac{16}{20}$