Answer:
The number can be many numbers like: 7,777,111 or 7,555,333 or 7,111,777
A: 7,777,111
We have four 7's and three 1's
\(7*4=28\)
\(1*3=3\)
\(28+3=31\)
B: 7,555,333
We have one 7, three 5's and three 3's.
\(5*3=15\)
\(3*3=9\)
\(15+9+7=31\)
These also can be 7,333,555 or 7,111,777.
