Answer:
Formula for nth term in Arithmetic sequences is:

where a is the first term, d is the common difference and n is the number of terms.
As per the statement:
The rule for the pattern is add 4.
As the first term in line says the first term i,e 7

common difference(d)= 7
As the Jenna number is 8th in line.
Series we get;
7, 11, .........
We have to find the 8th term.
n = 8, a = 7 and d = 4
Using above formula:

Therefore, 35 number should Jenna say.