There are 48 students in a play ratio of boys to girls is 5 to 7

Let's let "5x" represent the number of boys in the school play and "7x" represent the number of girls in the school play.  5x = boys 7x = girls  If we know that the total number of students in the play equals 48, then that must be that both the number of boys and girls combined must equal 48:  5x + 7x = 48 12x = 48 x = 4  Now, take your x-value and plug it into both the boys' and girls' values to figure out how many boys and girls there are in the play:  5x = 5 (4) = 20 boys 

7x = 7 (4) = 28 girls  To find out how many more girls there are than boys in the play, just subtract the number of girls minus the number of boys:  # girls - # boys = 28 - 20 = 8  This means that there are 8 more girls than boys in the school play