In a class of 47 students, the number of males is 7 less than twice the number of females. how many females and how many males are there in the class?

X=number of females
47-x=number of males
# of males is 2*(number of females)-7:
47-x= 2x-7
add x to both sides:
47=3x-7
add 7 to both sides:
54=3x
divide both sides by 3:
x= 18 females
47-18= 29 males