The lowest amount of significant figures has to be what the answer is...
7.6cm is 2 sig figs where 13.48 is 4, so the answer can only really be as precise as the smallest one (7.6)
7.6 + 13.48 = 21.08cm
Put it into 2 sig figs makes it
=21 cm (2s.f) <— don’t forget to write 2 sig figs next to it because otherwise it is a false answer