Interview of membership system in library

(2) Daily borrowing fee for library card: 50÷ 100=0.5 yuan,

It costs X yuan to rent a book and apply for a membership card every day.

Then 20+ 100x=50,

X = 0.3

(3) Book card y=0.5x,

Membership card y = 0.3x+20；;

(4)① Image method: take the intersection point A (80 80,0) as the AC⊥x axis,

At point C (80, y 1) it intersects with l 1, and at point B (80, Y 2) it intersects with l2.

As shown in the figure, > > y2 ..

Explain that it is more cost-effective to use a book rental card than a membership card.

(2) Borrow books for 80 days, and the card borrowing fee is 0.5×80=40 yuan.

Membership card costs 0.3×80+20=44 yuan.

Explain that it is more cost-effective to use a book rental card than a membership card.