A5. An entrepreneur has accepted an order that 8 workers could complete in 23 days. For the first three days, 8 workers were on the job site. After three days, two more workers joined them. In how many days will the entire work be completed?
(A) 10
(B) 19
(C) 20
(D) 25
(E) none of the above
A5. If 8 workers complete the work in 23 days, one worker completes in one day $\frac{1}{8}$ of $\frac{1}{23}=\frac{1}{8 \cdot 23}$ of the work. In three days, 8 workers complete $8 \cdot 3 \cdot \frac{1}{8 \cdot 23}=\frac{3}{23}$ of the work. $\frac{20}{23}$ of the work remains to be done, which 10 workers must complete in $x$ days: $x \cdot 10 \cdot \frac{1}{8 \cdot 23}=\frac{20}{23}$. The solution to the equation is $x=16$. The workers will complete the order in $3+16=19$ days.