Question 1087403

Let the number of boys be {{{b}}}.
Let the number of girls be {{{g}}}.

Each boy has as many brothers as sisters, then
{{{b-1 = g}}}......eq.1


but each girl has half as many sisters as brothers, so

{{{g-1= (1/2)b}}}

{{{g= (1/2)b+1}}}......eq.2


Solve the the system of equations by substituting for {{{g}}}:

{{{b-1 = (1/2)b+1}}}

{{{b-2 = (1/2)b}}}

{{{(1/2)b = 2}}}

{{{b = 4}}}-> the number  of boys


solve for {{{g}}}:

{{{g=b-1}}}

{{{g = 4-1}}}

{{{g = 3}}}-> the number of girls

the number of children in all {{{7}}}