The squirrel burrowed 6 holes in 2 minutes. To find how many holes the squirrel burrows in 7 minutes we multiply 6 x 3.5= 21.
Alternate method:
If the squirrel burrows 6 holes in 2 minutes that means he has burrowed 3 holes in 1 minute. Multiply the number of holes burrowed in 1 minute by 7 to get 21.