It is true because every term is the previous term multiplied by -2. So, -40 x -2 = 80, 80 x -2 = -160
You can estimate 7 2/5 to 7 and estimate 6 3/8 to 6 1/2. And add them both up. If u add them, you get 13 1/2
X+7<23
x<23-7
x<16
So, all numbers from zero to 15
Those are 16 positive integers