Step-by-step explanation:
Let there be x blue ribbons

I am sorry but I do not see the underlined digit, but I will put it this way. 7 in the thousands place is worth 7000, 2 in the hundreds place is worth 200, 7 in the tens place is worth 70, and 0 in the ones place is worth 0.
Hope this helped!
Nate
your answer is C. substraction
A, perhaps,plz check the definition of functions
D*pi so 6cm * pi which is ~18.849cm