Answer:
10 friends
Step-by-step explanation:
we know that
The formula of the sum is equal to
where
a1 is the first term
n is the number of terms (number of friends)
d is the common difference in the arithmetic sequence
In this problem we have
----> the common difference
substitute in the formula and solve for n
Solve the quadratic equation by graphing
The solution is n=10
see the attached figure
therefore
She had 10 friends who got stickers
