//Hope it helps and thanks for writing more specific.
39 foot into 3 pieces
one is 13 feet
the other pieces add up to the
remaining wire
which is 39-13=26 so
the two remaining pieces are x and y
one must be 2 less than 3 times the
other
x must be 2 less than 3 times the y
x=-2+3y
x=3y-2
x+y=remaining=26
26=x+y
x=3y-2
subsitute
26=3y-3+y
add like terms
26=4y-2
add 2 to both sides
28=4y
divide by 4
7=y
subsitute
7+x=26
subtract 7
x=19
19>7
7 feet is the legnth of the shorter
piece
