Question 1095496
<br>Let t = T-shirts, c = CDs, and b = books<br>
{{{t+c+b = 10}}}  the number of items is 10
{{{25t+10c+5b = 105}}}  the total cost ($25 for a T-shirt, $10 for a CD, $5 for a book) is 105
{{{t+c = b}}}  the number of books is equal to the combined number of T-shirts and CDs<br>
I'll let you solve the system of equations to find the answer to the problem.<br>
Note that the first and last equations together immediately give you the number of books; then substituting that number into the first and second equations gives you a system you can solve to find t and c.