:if a polygon consists of exactly two pairs of parallel sides, then the polygon must be a parallelogram rectangle quadrilateral trapezoid

Which pair of lines is parallel? a. y=4x+1 and y+4=5 b. y=-2+x and 2y-2x=-2 c. y=1/4x + 2 and y-2=1/2x d. y=1/5x+1 and 5y+x= 10

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )