Answer: y= -2ˣ + 4
Explanation:
You need to know how the parent function looks and then how it's been transformed. The image shows in red the parent function and the green is the new function.
You can see from the parent function, it's been flipped/reflected.
Also it's been shifted up 4
The formula is:
y = A * 2ˣ + k
where A is your stretch and where your reflection goes. No stretch but there was a reflection so
A = -1
k is your shift up or down, here you shifted up 4
Put it together:
y= -2ˣ + 4