1. The problem is to determine if the expression 4.3/4 uses a decimal point or a fraction bar. 2. The expression 4.3/4 can be read as "four point three divided by four". 3. The dot in 4.3 is a decimal point, indicating the number is four and three tenths. 4. The slash / represents division, so 4.3/4 means dividing 4.3 by 4. 5. Therefore, the dot in 4.3 is a decimal point, not a fraction bar. Final answer: The dot in 4.3 is a decimal point.