Explanation for Question 18 From the Math (No Calc) Section on the 2019 April Sat
For number 18, we are given this system of equations and it is asking 2 if M one P one is a solution. 3 What is the value of P one? So you're basically solving the equation for 4 P so I always like to use the method by adding and subtracting, 5 to cancel out a term. So I'm going to rewrite this top one, 6 three plus two P equals 24, 7 and then I'm going to multiply this bottom one by something to have the 8 3m cancel out. So if I multiply it by negative three, 9 then the 3m and the negative 3m will disappear when I add them. 10 So if I distribute that it'll give me negative 3m minus 11 three P equals negative 30. 12 Then if I add them 3m minus 3m, 13 that'll the zero to P minus three P gives me negative P 14 and 24 minus 30 is negative six. 15 So P is equal to six. 16 You could also use this method to eliminate P and solve for M 17 and then plug in your value of M to find P but that's a 18 whole extra step. And especially if you are running out of time, 19 this method eliminates M right away. 20 So you are solving for P in the first place.