At a college bookstore, Carla purchased a math textbook and a novel that combined cost a total of $54 ​
​The price of the math textbook, m is $8 more than 3 times the price of the novel,n .
​
​Which system of linear equations could be used to determine the price of each book?

we know that

case a) alternate exterior angles

m∠2=m∠7 --------> by alternate exterior angles

m∠1=m∠8 --------> by alternate exterior angles

case b) alternate interior angles

m∠3=m∠6 --------> by alternate interior angles

m∠5=m∠4 --------> by alternate interior angles

case c) corresponding angles

m∠1=m∠5 --------> by corresponding angles

m∠3=m∠7 --------> by corresponding angles

m∠2=m∠6 --------> by corresponding angles

m∠4=m∠8 --------> by corresponding angles

case d) vertical angles

m∠1=m∠4 --------> by vertical angles

m∠2=m∠3 --------> by vertical angles

m∠5=m∠8 --------> by vertical angles

m∠6=m∠7 --------> by vertical angles

therefore

the answer in the attached figure