Question

quantos múltiplos de 5 ha entre 101 e 199​

Answer 1

(105,110,... 195)

$\mathsf{a_{1}=105~~~r=110-105=5~~~a_{n}=195}$

$\mathsf{a_{n}=a_{1}+(n-1).r\to~n=\dfrac{a_{n}-a_{1}}{r}+1}$

$\mathsf{n=\dfrac{195-105}{5}+1=\dfrac{90}{5}+1}\\\large\boxed{\boxed{\boxed{\boxed{\mathsf{n=18+1=19}}}}}$