Why does this telescoping series end up with a 2 in the numerator?

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I am confused about how to solve for this series: $$f(x) = c/((x+1) (x+3))$$ for $x = 1, 2, 3...$ solving for $c$. I see this is a telescoping series with a result of $1/(x+1) - 1/(x+3)$ but the solution I was given for this problem says this is equal to $2/((x+1)(x+3))$ and I do not see how it arrives at that. Any advice please? Thank you!!