We can construct an expression for the weight of the puppy as follows:
*Since we have that the puppy gained a 10% of its original weight, we can determine that value (or write it) like this:
10% = 0.1, Here, 0.1 is a tenth of a unit, where the unit represents 100%. So, from this we write the expression:
![w=x+0.1x\Rightarrow w=1.1x](https://img.qammunity.org/2023/formulas/mathematics/college/932tq4eztyo7n1jyfwaxpjlr64d93vixkt.png)
Here w represents the weight and x the original weight of the puppy (First visit the vet), the reason that 0.1 multiplies x is because 0.1 represents 10% of the value it will multiply, for example:
If we want to know 10% of 100 units, we can multiply 100 times 0.1 and we will get the 10%, that is 100*0.1 = 10. Now, if we were to want to know 15% of 100 units we would multiply 0.15 times 100, that is 100*0.15 = 15; and so on.
After this, if the rate the puppy gains weight is the same (Another 10%), we would solve for the function as follows:
![w_1=w+0.1w\Rightarrow w_1=1.1w](https://img.qammunity.org/2023/formulas/mathematics/college/qpvsoxf257r0d0hf0w63udp1ceddi2ybku.png)
And, since we already know the weight of the puppy the previous visit to the vet, we replace the value as follows:
![\Rightarrow w_1=1.1(w+0.1w)](https://img.qammunity.org/2023/formulas/mathematics/college/lgi5m893nms0111ylu2qkphnyte7zx965t.png)
Now, we expand:
![\Rightarrow w_1=1.1w+0.11w](https://img.qammunity.org/2023/formulas/mathematics/college/aqyfve8tgru9u0wlj6033o5qp59t9lh2ws.png)
![\Rightarrow w_1=1.21x](https://img.qammunity.org/2023/formulas/mathematics/college/dz8ghn7yra17liatp9or9oxz7uxdavv7ce.png)
So, from this, we have that the weight of the puppy the third visit would be given by the expression previously described.