Jane is building a bookcase. she has one board that is 3 m 12 cm long and another that is 3 m 99 cm long. how long are the two boards together in meters?

when the 2 boards are put together, the total length will be 7 m 11 cm

Step-by-step explanation:

the first board has 3 m 12 cm, but since 1 m = 100 cm:

length board 1 = 3 m 12 cm = 3 * 100 cm + 12 cm = 300 cm + 12 cm = 312 cm

the same happens with the board 2

length board 2 = 3m 99 cm = 3 * 100 cm + 99 cm = 300 cm + 99 cm = 399 cm

the 2 boards together will have

total length = length board 1 + length board 2 = 312 cm + 399 cm = 711 cm

since 7 m = 700 cm

total length = 711 cm = 7 m 11 cm