Katrina is building a deck. she cuts 3 lengths of wood from a 72-inch board. the first length is 30 3/4 inches. the second length is 12 1/4 inches. and the third length is 16 1/4 inches. how much of the original board remains after katrina makes her cuts?

First add them together
30 and 3/4+12 and 1/4+ 16 and 1/4=30+3/4+12+1/4+16+1/4 =30+12+16+3/4+1/4+1/4=58+1+1/4=59+1/4=59 and 1/4
subtract from 72
72-59 and 1/4=72-(59+1/4)=72-59-1/4=71+1-59-1/4= 71-59+1-1/4= 71-59+4/4-1/4=12+3/4

the legnth left is 12 and 3/4 inches