I believe its 15 girls.
If its 5 girls to every 4 boys and there is 12 boys then 12 is just 4 three times so you would do 5 three times making it 15.
4boys = 5girls
+4boys= 5girls
+4boys = 5girls
=12boys = 15girls
Your mistake is that week 3 is twice of week 2
week2=x+5, twice of that is 2(x+5)=2x+10, you did not distribute the 2 to the 5 and you got 2x+5, that is your mistake
x is first week
2nd week is y
3rd is z
5 more the 2nd week than 1st week
x+5=y
3rd week is double 2nd wee
z=2y
total is 431
x+y+z=431
sub
y=5+x and z=2y
x+5+x+2y=431
sub 5+x for y
x+5+x+2(5+x)=431
x+5+x+10+2x=431
4x+15=431
minus 15
4x=416
divide by 4
x=104
add 4
x+5=109
double
2*109=218
they sold
1st week: 104
2nd week: 109
3rd week: 218
-2x - 2
Step-by-step explanation:
you would just have to plug in the 4 and -3 into the equation.