Answer Choices
a/b = -4/7
a/b = 10/7
a+b/b = 10/7
1-2b/b = -11/7
Explanation for Question 6 From the Math (No Calc) Section on the Official Sat Practice Test 4
Not for number six, we're given an expression right here and were asked, 2 which of the following must also be true. 3 And we see that we're not really solving particularly for one variable, 4 right? We're basically just maneuvering our variables around so that 5 it's either a over B or a plus B over B or a minus 6 to B over B. And so the easiest way to go about this problem 7 to start, it is going to be to start by looking at a versus 8 B, right? Because it's going to be easiest to maneuver this around so that 9 we have a over B setting up C and setting up D that gets 10 a little more complicated. So we'll start with a and B and we're going 11 to hope that one of those is right. And then if it's not, 12 we'll work our way towards sending up this form of the fraction, 13 but we'll start by rewriting it. 14 And we notice, you know, we have two fractions equal to each other, 15 so good. First step is going to be to cross multiply always. 16 So I have seven, eight minus B's equal to three B, 17 right? And then I'll distribute that 7, 7 80 minus seven B is equal 18 to three B. I'll get all my BS off to one side by adding 19 seven B to both sides that gives me seven, 20 eight is equal to 10 B. But now remember, 21 I don't want to solve for just a or just B. 22 I'm trying to create a fraction that looks like a over B. 23 So a has no coefficient, right? So I'll start by getting rid of the 24 seven on the, a by dividing those sides by seven. 25 And I want be on my other side now. 26 So I'm going to divide both sides by B that way the B gets 27 off of the right and onto the left side. And when I solve for 28 a over B, I get 10 over seven, which is what we see in 29 answer choice B. And so B is going to be our best answer. 30 And that means we don't even have to worry about the more complicated scene 31 D because we simply started by solving for a over B.