91Ó°ÊÓ

We need to find the cost of the t-shirt, video, and stuffed animal.

Let $x$represent the cost of one t-shirt, $y$represent the cost of the video, and $z$represent the cost of one stuffed animal.

The price $4$t-shirts, the video and $1$stuffed animal is $$135$. So the first equation is

$4x+y+z=135...\left(1\right)$

The price of $2$t-shirts, the video and $3$stuffed animals is $$115$. So the second equation is

role="math" localid="1644567844765" $2x+y+3z=115...\left(2\right)$

The price of $2$t-shirts, the video and $1$stuffed animal is $$85$. So the third equation is

role="math" localid="1644567949474" $2x+y+z=85...\left(3\right)$

Subtract the third equation from the first equation

$\begin{array}{rcl}4x+y+z-(2x+y+z)& =& 135-85\\ 4x+y+z-2x-y-z& =& 50\\ 2x& =& 50\\ x& =& 25\end{array}$

Substitute $25$for $x$in the second equation

role="math" localid="1644568140638" $\begin{array}{rcl}2x+y+3z& =& 115\\ 2×25+y+3z& =& 115\\ 50+y+3z-50& =& 115-50\\ y+3z& =& 65...\left(4\right)\end{array}$

Substitute $25$for $x$in the third equation

role="math" localid="1644568198641" $\begin{array}{rcl}2x+y+z& =& 85\\ 2×25+y+z& =& 85\\ 50+y+z-50& =& 85-50\\ y+z& =& 35...\left(5\right)\end{array}$

Subtract the fifth equation from the fourth equation

$\begin{array}{rcl}y+3z-(y+z)& =& 65-35\\ y+3z-y-z& =& 30\\ 2z& =& 30\\ z& =& 15\end{array}$

Substitute $15$for $z$in the fifth equation

$\begin{array}{rcl}y+z& =& 35\\ y+15& =& 35\\ y& =& 35-15\\ y& =& 20\end{array}$

So the price of one t-shirt is $$25$, the video is $$20$, and one stuffed animal is $$15$