5, 20, 35, 50, 65

To find the 50th term, use the formula: = + (n – 1) ⋅ d.

20 – 15 = 5

35 – 15 = 20

D= +15

= 5 + (50 -1) ⋅ 15.

= 5 + (49) ⋅ 15

= 5 + 735

= 740

Find with the formula =  ( + )

= ( 5 + 740)

= 25 (745)

= 18,625