Answer: 20c + 10.
Step-by-step explanation:
(c represents crates)
I wrote each equation separately first.
Supplier A: 4c + 6
Supplier B: 6c - 1
Supplier C: 10c + 5
We can add all the cs from each supplier giving us 4c + 6c + 10c which equals 20c. Now we can add the extra shoes as, 6 + (-1) + 5 equaling 10. I wrote -1 because we are missing that shoe, but you can write it as 6 - 1 + 5 instead. Together the two numbers make the equation 20c + 10. Hope that helps : )