For this case we have the following expression:
[tex]x + 10 = 45[/tex]
The last option tells us the following:
There are 45 students in a group. There are also 10 adults in the group. What is x, the total number of students and adults in the group?
So, the variable x can not represent adults and students because they tell us that 45 are clearly students. The equation is not fulfilled with this last option.
Answer:
Option D
