The local craft store purchased 7 boxes of red yarn, 5 boxes of yellow yarn, and 12 boxes of blue yarn. Each box contains 25 balls of yarn. How many balls of blue and red yarn did they order?

Ignore the boxes of yellow yarn, they're insignificant.

If each box has 25 balls in it, you would multiply the number of boxes by 25

First do the red balls: 7 x 25 = 175

Then the blue: 12 x 25 = 300

Now you add the red balls and the blue balls.

They ordered 475 balls of blue and red yarn. Or 300 blue and 175 red