Let M = amount of money in ATM at the beginning
M - 18(100) = M - 1800
The change is a decrease of $1,800
Step-by-step explanation:
Collinear points have the same gradient
find the gradient(slope) between AB first

Find the one for BC

Find the gradient between AC now

YOUR LAST STATEMENT NOW WILL BE
POINTS A,B AND C ARE COLLINEAR SINCE THE GRADIENTS BETWEEN THEM IS THE SAME!!!