The given statement is "the sum of 10 and two-thirds of that tree's age, in years, is equal to 50".
If a represents a tree's age, the expression that represents this situation is
![10+(2)/(3)a=50](https://img.qammunity.org/2023/formulas/mathematics/college/br4a17lbd3drewrynmz2v4vp4a5fh1hdr1.png)
Observe that the variable a has to multiply the fraction only.
Hence, the second option is correct: the variable a should be multiplied by 2/3 only and then added to 10.