That is nothing but basic addition. You should know that, if you're older than 8.
Three wires are 6.5 m, 8.19 m, and 4.457 m long. What is the total length of the wires? Give your answer with the appropriate precision. A. 19 m B. 19.0 m C. 19.1 m D. 19.147 m
check your notes, or text book. This is not just an addition question, it is also a question about significant figures.