Answer:
10 times.
Explanation:
The 1 in the 615 is in the tenths place.
The 1 in the 91 is in the ones place.
So, the one in the 615 is 10 times greater than the one in 91.
Look:
1x10 is 10, the 1 in 615 is basically 10, and the 1 in 91 is basically 1.