300 parents
3/4 = x/400, and we are trying to find x.
Multiply the numerator and denominator of 3/4 each by 100 to make the denominator equal 400. This gives 300/400. So, 300/400 = x/400.
Multiply both sides of the equation by 400 to cancel out the division. This gives you 300 = x, so 300 parents said yes to the survey.
