The ratio 4:3 can be expressed as a fraction by placing the first number (4) as the numerator and the second number (3) as the denominator. Therefore, 4:3 as a fraction is 4/3.
This fraction is already in its simplest form because 4 and 3 have no common divisors other than 1. So, 4/3 is the simplified fraction representation of the ratio 4:3.