Step-by-step explanation:
2 ways :
1. convert everything to inches, then do the calculation, and then convert the result back to feet and inches :
1 ft = 12 in
2 ft = 2×12 = 24 in
2 ft 11 in = 24 + 11 = 35 in
9 scarves need then
35 × 9 = 315 in
to convert back into ft and in, do a whole number (ft) division by 12 and mark the remainder (in) :
315 / 12 = 26 remainder (315 - 12×26 = 315 - 312 = 3)
26 ft 3 in are needed for 9 scarves.
2. do the calculation with both, the given ft and in, and then move any "full" ft from the inches to the feet :
2 ft 11 in × 9 = 18ft 99 in
to convert 99 into ft and in we use the same trick as at the end of 1. :
99 in / 12 = 8 remainder (99 - 12×8 = 99 - 96 = 3)
we need 18+8 = 26 ft plus 3 in = 26 ft 3 in for 9 scarves.
