She will need 7 93/100 more border. To solve you change it to decimals. 10 4/5 changes to 10.8 which means her 3 rolls has 32.4 feet of border. 40 1/3 changes to 40.3333333 and when you subtract 32.4 from that you get 7.93 which changed into a mixed number equals 7 93/100