There are infintely many equivalent equations to a given equation.
In fact, every time you perform a legit transformation on your equation, you have an equivalent equation. Legit transformations include, for example, adding/subtracting a same number from both sides, or multiplying/dividing both sides by any non-zero number.
In your case, we can expand the multiplications on both sides:
[tex]3(2x-5)= 4(x+3) \iff 6x-15=4x+12[/tex]
And these are two equivalent equations.
We can go on solving the equation adding 15 to both sides, and we get
[tex]6x=4x+27[/tex]
and this is another equivalent equation. Finally, we can subtract 4x from both sides:
[tex]2x=27[/tex]
and divide both sides by 2:
[tex]x=\dfrac{27}{2}[/tex]
All the equations we got in this example are equivalent:
[tex]3(2x-5)= 4(x+3)\\6x-15=4x+12\\6x=4x+27\\2x=27\\x=\dfrac{27}{2}[/tex]
are all equivalent.
