Answer: We are given:
During the first 10 days, the stock increases by $0.30 per day.
During the next 10 days, the stock decreases by $0.45 per day.
During the last 10 days, the stock increases by $0.25 per day.
We have to find total amount the stock increase over the first 10 days.
The total amount the stock increase over the first 10 days is:
![0.30 * 10](https://img.qammunity.org/2019/formulas/mathematics/college/87scfq4xwp468u1xv6buyhi4xbj7wachtj.png)
![\](https://img.qammunity.org/2019/formulas/mathematics/college/aa624vi2aymr5w7yum0glvbev4zn0qy7ed.png)
![3](https://img.qammunity.org/2019/formulas/mathematics/high-school/hbbf7ptcvkzqpizk1mcsdbejc8kcre7ia9.png)
Therefore, during the first 10 days the stock was increased by $3.