3.75 ft and 1.25 ft
Step-by-step explanation
Step 1
Diagram
Step 2
set the equations
let x represents the longest piece
lety represents the smaller piece
so
a)A carpenter cuts a 5-ft board in two pieces, hence

b)One piece must be three times as long as the other,then

Step 3
finally, solve the equations:
a) replace the x value from equation (2) into equation(1)

b) now, replace the y value into equation (2) to find x

therefore, the lengths of the pieces are
3.75 ft and 1.25 ft
I hope this helps you