3. a. It is a four-digit whole number.
b. It is greater than 4000.
c. the sum of its hundreds digit and its ones digit is 9.
d. Twice its tens digit is 2 more than its thousands digit.
e. The sum of one-fifth of its hundreds digit and two-thirds of its ones digit is 6.
f. Its tens digit is 1 less than its thousands digit.