Math
posted by Nina .
Not Urgent But Please Check My Answer:
A pencil at a stationery store costs $1, and a pen costs $1.50. Stella spent $21 at the store. She bought a total of 18 items. Which system of equations can be used to find the number of pencils (x) and pens (y) she bought?
I think it is this: x + 18y = 21
x = 1.5y
18x + y = 21
x = 1.5y
x + 1.5y = 21
x + y = 18
I know for a fact not this: 1.5x + y = 21
x = 18y

Math 
Bosnian
x = number of pens
y = number of pencils
She bought a total of 18 items.
x + y = 18
Stella spent 21 $
1.5$ * x + 1 $ * y = 21 &
1.5 x + 1 * y = 21
1.5 x + y = 21
You must solve system :
x + y = 18
1.5 x + y = 21
The solutions aree .
x = 6
y = 12
Proof :
6 * 1.5 $ + 12 * 1 $ = 9 $ + 12 $ = 21 $ 
Math 
Bosnian
OR if you write :
x = number of pencils
y = number of pens
then
x + 1.5 y = 21
x + y = 18
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