Question 1109113
you have 10 / (1/2) = 20 time settings.
you have 7 aperture settings.


the total number of different ways you could set the exposure for the photograph would be 20 * 7 = 140.


to see how this works, assume only 3 time settings and 2 aperture settings.


let the time settings be 1,2,3
let the aperture settings be f1, f2


total exposure setting would be 3 * 2 = 6.


they would be:


1f1, 1f2, 1f3
2f1, 2f2, 2f3


the same logic applies for 20 time settngs and 7 aperture settings, but there would be 140 of them, rather than just 6 in our example.


with time setting of 1/2 second, your aperture settings could be f1, f2, f3, f4, f5, f6, f7.


with time setting of 1 second, your aperture settings could be f1, f2, f3, f4, f5, f6, f7.


etc....., in time setting of 1/2 second increments up to a time setting of 10 seconds.


a time setting of 0 seconds is not included, since that would not be possible.


the lowest time setting is therefore 1/2 second and the highest time setting is 10 seconds.