The mission gives a percentage bonus to base credits earned, what you can see in Credits and XP tab in post battle report. There you also can see the modifiers. So for example when you have Scylla signal, which gives you +25%, it calculates those 25% separately from that base credit earnings. So this mission should give you fixed bonus of certain number of percentage of credits.    So from your options, it should be (ship credits x camo) + (ship credits x signal) + (ship credits x mission)