posted by allen on .
At the school store, 5 pens sell for $1.25. Which proportion will help find the cost of 12 pens?
What are your choices?
What do you think the answer is?
I say its c
5 pens / 12 pens = 1.25 dollars/x dollars
It helps to write the units, pens and dollars.
I claim a is correct
although I myself would have written the same thing as
5 pens/1.25 dollars = 12 pens/x dollars
which comes out the same
5 pens cost 1.25$
1.25/5=0.25$ Price of one pen
12*0.25=3$ Price of 12 pens