You do it because if you added before you multiplied your answer would be way out in the atmosphere. I'm not sure who invented that though...
multiply first, and then add
you are suppose to MULTIPLY on area.
multiply
You multiply.
you can multiply 281 and 3 you can add 840 and 3
multiply first, and then add
you are suppose to MULTIPLY on area.
Multiply
multiply
multiply
You multiply.
Multiply for the area, add for the perimeter.
you can multiply 281 and 3 you can add 840 and 3
you add
Add.
You multiply them.
multiply