Question 869180
We can write each of the statements as an equation
1. Joel {{{j}}} has twice the number of CDs as Mariella {{{m}}}, hence
&nbsp;&nbsp;{{{j=2m}}}<br>
2. Joel's number of CD's - 7 divided by 3 equals the number of CDs Blake {{{b}}} has:
&nbsp;&nbsp;{{{(j-7)/3=b}}}<br>
3. Blake has 25 CDs
{{{b=25}}}
<br>
Substituting (3) into (2) gives:
&nbsp;&nbsp;{{{(j-7)/3=25}}}
&nbsp;&nbsp;{{{j-7=3x25}}}
&nbsp;&nbsp;{{{j-7=75}}}
&nbsp;&nbsp;{{{j=75+7}}}
&nbsp;&nbsp;{{{j=82}}}<br>
So Joel has got <b>82</b> CD's<br>
Based on equation (1) we can calculate the number of CD's Mariella has:
&nbsp;&nbsp;{{{82=2m}}}
&nbsp;&nbsp;{{{m=82/2}}}
&nbsp;&nbsp;{{{m=41}}}
<br>
Mariella has <b>41</b> CDs
Joel has <b>82</b> CDs
Blake has <b>25</b> CDs