When rounding a number, we first find the digit in the place value we're rounding to. In this problem, we are rounding to the tenths place; the digit in the tenths place is 2.
The next thing we do is look at the digit to the right of the place value we're rounding to. If this digit is 5 or more, we round our place value up; if it is 4 or less, we leave our place value alone. The number to the right of the 2 is 9; since this is in the "5 or more" category, we round the 2 up to 3.
The last step is to drop the digits to the right of our place value. This gives us our final answer of 43.3.
