Question

solve. the average age of a husband, wife and their pet dog is 21 years. if the average age of the husband and wife is 26 years, how old is the dog?

Answer 1

Dear student
$$\begin{gathered} \mathrm{Average}\mathrm{age}\mathrm{of}\mathrm{husband},\mathrm{wife},\mathrm{dog}=21\mathrm{years} \\ \mathrm{Sum}\mathrm{of}\mathrm{ages}=21\times 3=63\mathrm{years} \\ \mathrm{Average}\mathrm{age}\mathrm{of}\mathrm{husband}\mathrm{and}\mathrm{wife}=26\mathrm{years} \\ \mathrm{Sum}\mathrm{of}\mathrm{agaes}=26\times 2=52\mathrm{years} \\ \mathrm{So},\mathrm{age}\mathrm{of}\mathrm{dog}=\left(63-52\right)\mathrm{years}=11\mathrm{years} \end{gathered}$$
Regards