13, each term is the sum of two preceding ones.
I think it would require 100 workers since 1 worker digs up 1 yard.
Hope this helps.
You have to solve this algebraicly.
To do this set up the proportion and add x to each term.
You get 4x and 7x
Set this equal to 33
4x+7x=33
Combine like terms and get 11x=33
Divide by 11
x=3
Now go back to 4x and 7x
Multiply them by x and get 12(4×3=12) and 21(7×3=21)
One group is 12 and the other is 21.
The first one means what is the smallest number that goes into 12 which would be 4. The second one mean what does not go into 4 and 6 so that would be 8 because 6 is not a multiple of 8.The third one is either 1 or 2 not sure. And the 4th one is little complicated you might want to look up video on prime factorization that can really help you .
