Answer :
[tex]b-boys\\g-girls\\\\ \left\{\begin{array}{ccc}b+g=51\\2g=b+12\end{array}\right\\\\+\left\{\begin{array}{ccc}b+g=51\\2g-b=12\end{array}\right\\----------\\.\ \ \ \ \ \ 3g=63\ \ \ \ /:3\\.\ \ \ \ \ \ g=21\\\\Answer:21\ girls.[/tex]
x- amount of girls
y-amount of boys
x+y=51
y+12=2*x
From first equation:
x=51-y
substitude to second:
y+12=2*(51-y)
y+12=102-2y
3y=102-12
3y=90 /:3
y=30
x=51-30=21
There are 21 girls.
y-amount of boys
x+y=51
y+12=2*x
From first equation:
x=51-y
substitude to second:
y+12=2*(51-y)
y+12=102-2y
3y=102-12
3y=90 /:3
y=30
x=51-30=21
There are 21 girls.
