Step-by-step explanation:
To solve this first we have to eliminate the parenthesis using the distributive property in the subtraction on the right side. Also, I'll write the decimal coefficient 0.25 as a fraction 1/4:

Now we have to put all the x's on the same side of the equation and the numbers on the other side:

Now we divide both sides by 15 and multiply both sides by 4:

Answer:
x = 12