Plates of numbers overlap. Where two meet, the two numbers there are added; in the middle, all four.
Each overlap shows two numbers: what it makes now, then the sum it asks for. 7/14 makes 7 and wants 14. Touch the left half of a plate to turn it back, the right half to turn it on, or press its key.
Turning one plate fixes one overlap and disturbs the next. One arrangement satisfies them all. Above the plates are the fewest turns that would get there and the turns you have left; run out of turns and the day is lost.