Final answer:
The simplified form of the expression r-7+5-12 is r - 14, achieved by combining the constants, which is option B r - 14.
Step-by-step explanation:
The simplified form of the given expression r-7+5-12 is obtained by combining the like terms. Since -7, +5, and -12 are all constants, we can add and subtract them. The expression simplifies as follows:
r + (-7 + 5 - 12)
r + (-7 + 5) + (-12)
r + (-2) + (-12)
r - 2 - 12
r - 14.
Therefore, the correct option is B. r - 14.