For this case we have that by definition, a linear equation is of the form:
![y = mx + b](https://img.qammunity.org/2020/formulas/mathematics/high-school/fc4cgm6covys37zv2opmmp9ps4jxyjepvh.png)
Thus, we have the following options:
Option A:
![\frac {2} {3xy} - \frac {3} {4y} = 0](https://img.qammunity.org/2020/formulas/mathematics/high-school/p5lukm4o80jfzjzw4rohkwzzl70y46y3y9.png)
It is not a linear equation !!
Option B:
![3a + 5b = 3\\5b = 3-3a\\b = - \frac {3} {5} a + \frac {3} {5}](https://img.qammunity.org/2020/formulas/mathematics/high-school/jql62vjzl6vdvjn3gynmszhuxber8h4zud.png)
It is a linear equation!
Option C:
![4m ^ 2 = 6](https://img.qammunity.org/2020/formulas/mathematics/high-school/k9xdlb8yf9od250nktgz2h1asz9fk0alp7.png)
It is a quadratic equation, the exponent of the variable is 2.
Option D:
![x ^ 2 + y ^ 2 = 0](https://img.qammunity.org/2020/formulas/mathematics/high-school/glo3e7uyvjiwfw0a5a8pvjvtnrwm6q8nma.png)
It is a quadratic equation, the exponents are quadratic!
Answer:
Option B