(11k^4 - 4m) + (-2k^4 - 15m)
Add -2k^4 to 11k^4. This would be the same as subtracting 2k^4 from 11k^4
9k^4 - 4m - 15m
Add -15m to -4m. This would be the same as subtracting 15m from -4m
Final Answer: 9k^4 - 19m
Word Form: Nine times the variable k to the forth power minus nineteen times the variable m.