5X-20=4X+7
5X-4x=20+7
X=27°
Answer:
The correct answer is (edit: b).
Step-by-step explanation:

Answer: Store B
Step by Step
divide the the normal price of the book by four to get the amount of the book on sale in store B which is $21. To get the answer for Store A divide the normal price of the book by ten then divide the amount you get by 2 and add the two amounts up to get the the amount of the book on sale which is $21.26
If two sides and the included angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.