The shirts were sold at $15 each. 
        
             
        
        
        
Answer:
x=5
y=12
Step-by-step explanation:
the equation is
12x-5+125=180
12x+120=180
12x=60
x=5
According to the question
8y+29=125
8y=96
y=12
 
        
                    
             
        
        
        
8.) The answer would be 53.
I don't know 9 so sorry. 
        
                    
             
        
        
        
Given the system of equations:

To solve it by substitution, follow the steps below. 
Step 1: Solve one linear equation for x in terms of y. 
Let's choose the second equation. To solve it for x, add 3y to each side of the equations.

Step 2: Substitute the expression found for x in the first equation.

Step 3: Isolate y in the equation found in step 2. 
To do it, first, add 48 to both sides.

Then, divide both sides by 15.

Step 4: Substitute y by 5 in the relation found in step 1 to find x. 

Answer:
x = -9 
y = 5
or (-9, 5)
Also, you can graph the lines by choosing two points from each equation, according to the picture below.
 
 
 
        
             
        
        
        
You would do for pens
22 x 1.15 =25.30
And for markets
15 x 2.05 = 30.75
 
And since you are trying to find how much he spent in all you would add the two sums
25.30 + 30.75 = 56.05