Question 992568
Let J be the number of CDs jacob owns.
You are told sam has J-24. 

You are also told that {{{(J-4) = 1.5(sam)}}}
{{{J-4 = 1.5(J-24)}}}
{{{J-4 = 1.5J - 36}}}
{{{32 = 0.5J}}}
{{{64 = J}}}

jacob owns 64 CDs. sam owns 64-24 = 40

together they own 104 CDs