I used an alternative approach. Since our time is heavily constrained, I try to avoid drawing graphs unless absolutely necessary.
Statement 1: a>2b
let's say b=0.
Now, any positive value of 'a' will satisfy Statement 1.
Substituting 'b' for 'y', which we can do since (a,b) corresponds to (x,y), we have the following:
1-x < 2(0), or 1-x < 0.
Another way to say this is "1-a < 0".
If a > 1, this is true.
If 1 > a > 0, this is false
Statement 1 is insufficient.
Statement 2: b=1
Substituting 'b' for 'y', we get the following:
1-x < 2(1), or 1-x < 2
Another way to say this is "1-a < 2"
If a > -1, this is true
If a <= -1, this is false
Statement 2 is insufficient.
Combining the two statements, we know that:
b = 1
a > 2
Another way of saying this is:
y = 1
x > 2
From the original equation (or Statement 2), "1 - x < 2".
Since x > 2, any such value of 'x' will satisfy this statement.
Combining Statements (1) and (2) is sufficient
I'm really old, but I'll never be too old to become more educated.
