Verified answer

[tex]\displaystyle\bf\\c_{1} =3\\\\q=5\\\\c_{2} =c_{1} \cdot q=3\cdot 5=15\\\\c_{3} =c_{2} \cdot q=15\cdot 5=75\\\\c_{4} =c_{3} \cdot q=75\cdot 5=375\\\\Otvet: \ 3 \ ; \ 15 \ ; 75 \ ; \ 375[/tex]