just to make it clear tenths refer to the decimals. therefore,
since the number is 3.3,
given 3 is ones, that would make 3 as tenth
given 13 is tenths, it means its 1.3. therefore when you subtract it from 3.3, it would make 2 as ones.
given 1 is ones, 23 would be tenths. same like the second question.
and lastly if 0 is ones, tenths would be 33