SAT Subject Test Mathematics Level 2

Usually the best thing to do to start on a plane geometry question is to mark up the figure. Put as
much of the information into the figure as you can. Doing so is a good way to organize your
thoughts and avoid having to go back and forth between the figure and the question.

Now you can plan your attack. First subtract from the whole length to get :

    =       −       =   (3a +   15) −   (7a +   5)  =   3a  +   15  −   7a  −   5   =   −4a +   10

MARK UP THE FIGURE

Try to  put all the given   information into    the figure  so  that    you can see everything  at  a   glance

and don’t   have    to  keep    going   back    and forth   between the question    stem    and the figure.

Then, because Y is the midpoint of , you can divide by 2 to get and :

Watch out! That matches choice (B), but is not the final answer. What you’re looking for is , so
you have to add:

    =       +       =   (7a +   5)  +   (−2a    +   5)  =   5a  +   10

The answer is (E).

BASIC TRAITS OF TRIANGLES