How can completing the square aid in solving quadratic functions?

Consider the proof. given: segment ab is parallel to line de. prove: what is the missing statement in step 5?

Put the equation in slope intercept form by solving for y

Aclothing store has the sign shown in the shop window. pani sees the sign and wants to buy 3 shirts and 2 pairs of jeans. the cost of each shirt before the discount is $12, and the cost of each pair of jeans is $19 before the discount. write and simplify an expression to find the amount pani pays if a $3 discount is applied to her total