We are given a decimal number P = 12.abc where a, b, and c are the ten

I can answer this..
(1) just tells us about b, nothing about c, so not sufficient.
(2) tells us that 10P = 12a.bc = 124.7, so we can infer that a = 4. But, b can be 6 and c can be > 5 and rounding to the nearest tenth would give us b as 7; or we could have b = 7 and c < 1 s.t rounding gives us b = 7. So (2) by itself is also not sufficient.

Looking at both of the statements together, we know that b can't be odd, and b has to be < 9 (digit) so b can be 2, 4, 6, 8. 2 and 4 are eliminated because it can't give us 7 when rounding. If b = 6, and c > 5, rounding will give us b = 7. If b = 8, no value of c can give us b = 7 (because if c <5, b= 8 and if c > 5, b = 9). Therefore, b = 6 and c>5. The smallest value of c is 6, and 6+5 > 9, hence both statements together are sufficient.