A temporary worker was hired at the rate of Rs. 100 per day for a period of 30 days. If he remained absent, a sum of rs. 25 was deducted from his salary per day. If he recieved Rs. 2825 at the end of 30 days, for how many days was he present?[ Experts, please do not give a link related to this. Please just solve it ]

let the worker was present for x days, therefore he was absent for 30-x days.
therefore the amount given to him is $100x-25*(30-x)=100x-750+25x=125x-750$
it is given that he received Rs 2825 at the end of 30 days.
therefore:
$$\begin{gathered} 125x-750=2825 \\ 125x=2825+750 \\ 125x=3575 \\ x=\frac{3575}{125}=28.6 \end{gathered}$$

please again check your question, the amount received must be Rs. 2875, so that we can find the number of days as an integral value.
if the amount received is Rs. 2875
$$\begin{gathered} 125x-750=2875 \\ 125x=2875+750 \\ 125x=3625 \\ x=\frac{3625}{125}=29 days \end{gathered}$$

hope this helps you