A 39-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