Answer:A) Step-by-step explanation:Given expression:[tex] \boxed{\mathsf{c = 15 + am}}[/tex]subtracting 15 from both sides, and combining like terms on the RHS[tex] \implies\mathsf{c - 15 = (15 - 15)+ am}[/tex]Dividing both sides by a[tex] \implies\mathsf{ \frac{c - 15}{a} = am \times \frac{1}{a} }[/tex]a On the RHS gets canceled for being present in both Numerator as well as denominator, and were left with the following equation:[tex] \implies\mathsf{ \frac{c - 15}{a} = m }[/tex]