> > The number of boys in ninth grade is 12 less than twice the number of girls.

# The number of boys in ninth grade is 12 less than twice the number of girls.

## There are 51 students in ninth grade. How many are girls?

144 Views

### The number of boys in ninth grade is 12 less than twice the number of girls.

There are 51 students in ninth grade.
How many are girls?

$$b-boys\\g-girls\\\\ \left\{\begin{array}{ccc}b+g=51\\2g=b+12\end{array} ight\\\\+\left\{\begin{array}{ccc}b+g=51\\2g-b=12\end{array} ight\\----------\\. \ \ \ \ \ \ 3g=63\ \ \ \ /:3\\. \ \ \ \ \ \ g=21\\\\\ girls.$$