The lengths in feet of three ropes are consecutive multiples of three. If each rope were four feet shorter, the sum of their lengths would be 42 feet. Find the lengths of the three ropes.

Answer 1

let the length be x-3, x, and x+3

had each been 4 ft shorter, they would have been:
x-7, x-4, and x-1

x-7 + x-4 + x-1 = 42
3x = 54
x = 18

the ropes are 15, 18 and 21 ft each