Apencil at a stationery store costs $1, and a pen costs $1.50. stefan spent $7 at the store. he bought a total of 6 items. which system of equations can be used to find the number of pencils (x) and pens (y) he bought?

Y= # of pencils 
z= # of pens
1y + 1.50z = 7
Total # of pencils and pens combined equals 6 
4 pencils = $4
2 pens = $3 
$4 + $3 = $7 
4 pencils + 2 pens = 6 items total

Let pencil represent x
pen represent y
Next, we have this two equation:
x+1.5y=7
x+y=6
Then, I will use substitution to find the value of x and y:
x+1.5y=7
-
x+y=6
=
0.5y=1
y=2 pens
x+y=6
x+2=6
Subtract 2 for both side
x+2-2=6-2
x=4 pencils
Check:
x+y=6 items
4+2=6 items Right

x+1.5y=7
4+1.5(2)=$7
$4+$3=$7
$7=$7
As a result, there are 4 pencils , and 2 pens. Hope it help!