Given: W can do 25% of work in 30 days. X can do 1/4 of the work in 10 days. Y can do 40% of the work in 40 days. Z can do 1/3 of the work in 13 days. Step-by-Step Calculation: W's rate of work: W can do 25% of work in 30 days. $30/(\frac{25}{100})$ Result: 120 days

X's rate of work: X can do 1/4 of the work in 10 days. $=10/(\frac{1}{4})$ Result: 40 days

Y's rate of work: Y can do 40% of the work in 40 days. $=40/(\frac{40}{100})$ Result: 100 days

Z's rate of work: Z can do 1/3 of the work in 13 days. $=13/(\frac{1}{3})$ Result: 39 days. Therefore, Z completed the work first