You could
create a equation such below:
y= 50x+20
Next, put
12 in both y=50x+20 and y=15x+80
Then,
y=50x+20=50 · 12+ 20=600+20= 620
y=15x+80=15 · 12+ 80=180+80= 260
Compare
these two, it's clearly that the second one is cheaper
Answer:
The camera in the second store is cheaper.
