Step-by-step explanation:
For solving, use quadratic formula
Answer:

Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or 
so
For 
substitute
------> 
therefore

7. If each sister has one brother, it would be one brother total, because they are all related. They don't each have their own brother. So mom+dad+sisters(4)+brother=7 total.
hope this helped :)