Problems on Ages Practice Test 1 with solutions

Let age of the baby is $\mathit{x}$.
3 years ago total age of the family $=5\times 17=85$ years
Total age of the 5 member at present time, $=85+3\times 5=100$ years
Total age of the family at present time including baby, $=100+\mathit{x}$
The average of the family including baby at present time, $=17$ years
$\frac{100+\mathit{x}}{6}=17$
$100+\mathit{x}=102$
$\mathit{x}=102-100=2$ years