Answer:
26 ft.
Step-by-step explanation:
1) First I would suggest swapping 8 and 2/3 from a mixed number into a fraction:
8 2/3=8+2/3=(24/3)+(2/3)=26/3
2) Next you just need to multiply the number of shelves John wants to make by the required amount of lumber. He wants to make 3 shelves and each one requires 8 2/3 ft. of lumber, which(as we found above) is 26/3 ft. of lumber:
3×(26/3)=26
So John will need 26 ft. of lumber for his shelving.