Question

„Ms. Karone orders a total of 350 black, blue, and red pens for the school.

• She orders 170 black pens.
• She orders 120 blue pens.
Which equation can be used to find r, the number of red pens Ms. Karone
orders?
350 - 170 – 120 =r
350 + 170 + 120 =
350 – 170 + 120 = r.
350 +170 – 120 = r

Answer 1

350 - 170 – 120 = r

Explanation:

Since there is a total of 350 black, blue, and red pens, and we know how many black and blue ones there are, this can be used to find the number of red ones.

350 - 170 – 120 = r can be used to find the number of red pens, because if you subtract the amount of black pens (170) and the amount of blue pens (120) from the total, that will leave you with r, the amount of red pens.

So, 350 - 170 – 120 = r is the correct equation.