i am trying to calculate simple problem from physic,but i am getting somehow wrong answer.problem is that what is a mass of bag which is hold by child with mass $50$KG,if there is force of heaviness on both which is equal $600$N
so in shortly,we know that on child and bag,there works $600$N force of heaviness,we have to find mass of bag. as i know force of heaviness on mass on earth is $F=m*g$ if we have two mass,then i think formula would be $F=m_1*m_2*g$ from which $m_2=1.2$,but in book answer is $m_2=10kg$,please help me to clarify why is so?