Standard form: ax+by=c
With standard form there are a few rules One being ax and by cannot be fractions. Two being ax has to be positive.
Now ill explain the problem.
y=-1/2x-5 ↔ You will need to multiply the whole problem by 2 which will leave you will this 2y=-2x-10
Next you will need to move x over to the y side which will look like this 2x+2y=-10 (your answer)
Now you might be asking where the - went that was in front of the x term. Another rule is when you move across the equal sign you change the sign.
Let me know if this helped!