Answer
See below.
Work Step by Step
We know that $a_n=a_1+(n-1)d.$
where $d$=common difference and $a_1$= the first term
Hence, here we have
$a_n=3+(n-1)\cdot2=3+2n-2=2n+1$
Therefore $a_5=2\cdot5+1=10+1=11$
$a_{50}=2\cdot50+1=100+1=101$