Pwn the sat 4th edition page 36 question 3

Pwn the sat 4th edition page 36 question 3

I am tutoring my sophomore on her SAT math and we are going through your book a page at a time.

This problem is under back solving.
Given the amount of time you need to spend multiplying the left hand side of the equation. Wouldn’t it be faster to solve for a than plugging in the values?

How would you approach this differently?
Thanks

Hard questions on the new SAT might look something like this

Even though very little information has been released to date—not even a full practice test yet!—I’m hard at work trying to get a head start on the next iteration of the Math Guide for the new SAT (coming about a year from now—March 2016). When I write questions, I have a very hard time keeping (more…)