Answer:
1:5
Step-by-step explanation:
Their is 2 red pens, because 20(pens) - 8(blue pens) = 12(pens [blue excluded]) and there are 10 black pens (12 - 10 = 2)
So we can get an un-simplified ratio of 2:10, however in the list of answers you gave us:
Their is no 2:10, so now we need to simplify our ratio by dividing both 2 and 10 by 2, 2 divided by 2 = 1 and 10 divided by 2 = 5. As we can now see this gives us the ratio of 1:5 which is our second answer choice, and therefore since 1:5 is equal to 2:10 our answer is 1:5
