w-ciagu-arytmetycznym-leftanright-dane-sa-a12-oraz-displaystyle-a22

$a_7=3$a_7=3

$\displaystyle a_7=3 \frac{1}{5}$\displaystyle a_7=3 \frac{1}{5}

$\displaystyle a_7=3 \frac{2}{5}$\displaystyle a_7=3 \frac{2}{5}

$a_7=4$a_7=4