Answer:
156 were there on the fourth day.
Explanation:
125% of the number she received on the previous day
This means that the previous day number is multiplied the 125%/100% = 1.25.
64 responses the first day
This means that the number of responses after x days is given by:
![R(x) = 64(1.25)^x](https://img.qammunity.org/2022/formulas/mathematics/college/bgpoukx5io7rpsbdt604ul0m3umx9vegn5.png)
How many were there on the fourth day?
This is R(4). So
![R(4) = 64(1.25)^4 = 156](https://img.qammunity.org/2022/formulas/mathematics/college/zdphr9o2wlagbbz4f1v9m3a9b3shln8bw8.png)
156 were there on the fourth day.