Since its 3/4 serving and there are 18 pancakes 18 divided by 3/4 just find the reciprocal (switch the denominator and numerator) and change divide to multiply 18 x 4/3 = 24 servings the reason being for multiplying the reciprocal: there is a rule stating that whenever you divide something by a fraction, you change the divide sign to a multiplying sign and flip the flip the digits in the numerator and denominator section in the fraction (basically the fractions reciprocal)
or another way of doing it is 3/4 = 0.75 18/0.75 = 24 but you'll likely to need a calculator for that
=6.333