A39-foot-long speaker wire is to be cut into three pieces. one piece is to be 13 feet long. of the remaining pieces, one must be 2 feet less than 3 times the length of the other. find the length of the shorter piece

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