Chapter 7 - Exponents and Exponential Functions - 7-1 Zero and Negative Exponents - Practice and Problem-Solving Exercises - Page 423: 68

The answer is 141$m^{-2}$, or $\frac{141}{m^{2}}$

To solve the expression: $\frac{6}{m^{2}}$ + $\frac{5m^{-2}}{3^{-3}}$ = $\frac{6}{m^{2}}$ + $\frac{5\times3^{3}}{m^{2}}$ = $\frac{6+(5\times27)}{m^{2}}$ = $\frac{6+135}{m^{2}}$ = $\frac{141}{m^{2}}$ or 141$m^{-2}$