Final answer:
To solve the equation 5+m=8 by isolating the variable, subtract 5 from both sides to find that m=3. So the correct answer is m=3.
Step-by-step explanation:
To solve the equation 5+m=8 by isolating the variable, we need to get rid of the number 5 on the left side of the equation. Since 5 is added to m, we can subtract it from both sides of the equation to keep it balanced. This will give us:
5+m-5=8-5
m=3
So the correct answer is m=3.