A French class has a total of

39

students. The number of males is

13

more than the number of females. How many males and how many females are in the class?

F=number of females

m=number of males

total is 39

m+f=39

males is 13 more than females

m=13+f

subbsitute 13+f for m

m+f=39

13+f+f=39

13+2f=39

minus 13 both sides

2f=26

divide both sides by 2

f=13

13 females

m=13+f

m=13+13

m=26

13 females and 26 males

If the number of males is x and the number of females is y,

x-13=y

x+y=39. Substituting x-13 for y, we have x+x-13=39 and by adding 13 to both sides we get 52=2x and dividing by 2 we get x=26