You may either multiply the numbers or the place value, and both methods will yield the same answer.
(2 thousands, 7 tens) multiplied by 10 results in
... (20 thousands, 70 tens)
or
... (2 ten-thousands, 7 hundreds)
It's false due to the squares being reduced to their minimum values.
The bathtub's depth measures 18 inches
It takes 2 minutes to fill 3 inches of the bathtub
Subsequently
The remaining depth needed for filling with water = (18-3) inches
= 15 inches
The time needed to fill the remaining 15 inches of the bathtub = (15*2)/3 minutes
= 30/3 minutes
= 10 minutes
Therefore, John is right in believing that it will require an additional 10 minutes to fill the tub to the brim at the same rate.
Hope this clarifies things!