A small fast charges an admission fee for children and adults. The cost for admission is $3 per adult and $2 per child. On a certain day, total admission fees were $900, and 350 people attended the fair How many children attended the fair that
day?
80 children
150 children
200 children
320 children

Taking algebra two apex courses and need with these questions

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?