Question 1039328
This is an arithmetic sequence with common difference d=(9-2)=7 (we subtract any two subsequent terms).
The nth term is calculated as follows:
{{{an=a1+(n-1)*d}}}
The sum of the first n numbers is
{{{Sn=(n/2)*(2*a1+(n-1)*d)}}}

In our case, Sn=335, a1=2 and d=7,
Therefore:
{{{335=(n/2)*(4+(n-1)*7)}}} and by solving the quadratic equation {{{7*n^2-3*n-670=0}}} we get n=10 (by keeping only the positive root).
So the answer is 10 terms.