[tex]F=ma\\\\a.\\ma=F\qquad|\text{divide both sides by}\ a\neq0\\\\m=\dfrac{F}{a}\\\\b.\\F=-30,\ a=6.\ \text{Substitute}\\\\m=\dfrac{-30}{6}=-5\\\\c.\\ma=F\qquad|\text{divide both sides by}\ m\neq0\\\\a=\dfrac{F}{m}\\\\F=30,\ m=10.\text{Substitute}\\\\a=\dfrac{30}{10}=3[/tex]
