The number of terms common between the two series    2 + 5 + 8 + …up to 50 terms and the series   3 + 5 + 7 + 9 + …. upto 60 terms.

Let $m^{th}$  term of first  A.P. be equal to the $n^{th}$ term of the second A.P. then 
2 , 5 , 8 ,….50 terms series  1
3 , 5 ,7 , …., 60 terms series 2  
Common series  5 , 11, 17 , ….., 119
${40}^{th}$term of series $1={\text{ 59}}^{\text{th}}$   term of series 2 = 119 = last term of common series 
 $\Rightarrow$$a_n=5+(n-1)d\Rightarrow 119+1=6n\Rightarrow n=20.$ 
$\therefore$       Number of common terms is 20.