Word Problem (Inverse Proportions) This is the problem:
There is a job that has to be made in 60 days by a group of workers. After one day of work five workers more are added to the original group and they work one day. After this second day of work another 5 workers are added to the group, and then they work together and finish the job one day before the planned date. How many workers were there in the original group?
I tried to do like this: each worker of the original group of m workers did 1/(60m) of the whole job during the first day. Then the second day there were m+5 workers so they did $\frac{1-\frac{1}{60m}}{59(m+5)}$ of the job, and  in the last day there already were m+10 workers who then worked 57 days (so the total ammount of days is 59...I think), so I tried to add the above quantities and came nothing close to the solution.

One day for the whole group was saved by adding $5 \cdot 58 + 5 \cdot 57$ days by one worker. So there were originally $5 \cdot 58 + 5 \cdot 57 = 675$ workers.
