Answer :

Porshia
The answer is 40.
Steps:
1. Look at the tens place which has the number 4
2. Look at the number behind it
3. Since, the number is 3, you round down to 40
( if your number is less than 5, you round down)
SchwarzschildRadius
So,

We need to round 43 to the nearest ten.

Look at the number in the one's place.  If the number is greater than or equal to 5, round up.  If the number is less than 5, round down.

43 rounded to the nearest ten is 40.