Please help me I don't under stand this question

What is the y-intercept of the line given by the equation

Suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet.

Rewrite the following quadratic functions in intercept or factored form. show your work. f(x) = 3x^2 - 12