Answer:
Step-by-step explanation:
1. bottom left
The element is Boron(B)
This is because on the periodic table, it shows that Boron has 5 protons and 5 electrons
For the given equation, either 3x + 7 = 0 or x + 7 = 0
Now,
or
So, possible values of x is : -7 and -7/3