First, we need to determine the time it takes for each girl to mow one lawn.
For Betty:
4 lawns in 4.4 hours, so 4.4 hours ÷ 4 lawns = 1.1 hours per lawn.
For Jemma:
6 lawns in 5.4 hours, so 5.4 hours ÷ 6 lawns = 0.9 hours per lawn.
Now, we need to find the time it takes for each girl to mow 7 lawns.
For Betty:
7 lawns × 1.1 hours per lawn = 7.7 hours.
For Jemma:
7 lawns × 0.9 hours per lawn = 6.3 hours.
Finally, we need to find the difference in time between Betty and Jemma:
7.7 hours (Betty) - 6.3 hours (Jemma) = 1.4 hours.
So, the correct answer is B. Jemma will take 1.40 hours less than Betty to mow 7 lawns.