I’m pretty sure it would be C
Answer:
D. Miko found an incorrect quotient and checked her work using multiplication incorrectly
Step-by-step explanation:
We are given the equation

This can be rewritten as

Miko's work is incorrect as she did not multiply by the reciprocal of denominator's fraction. Instead she just multiplied by that fractions.
No 1+2=3 which is less than 5
The two sides must equal more than the third one when added
I believe it’s C, 21 divided by 7. This one doesn’t leave any extra mugs out cause 21 divided by 7 is 3, leaving 7 mugs per 3 shelves and having none left.