I excluded the step of plugging in the initial velocity as the constant. After plugging it in, I get
9.92 + 3.24 m/s = 13.16 m/s = 13.2 m/s$$9.92 \,\frac{\mathrm m}{\mathrm s}+ 3.24 \,\frac{\mathrm m}{\mathrm s} = 13.16 \,\frac{\mathrm m}{\mathrm s} \approx \boxed{13.2 \,\frac{\mathrm m}{\mathrm s}}$$
credit: erenust
