The word "more" in this context means we want to find the difference between the number Daria has and the number Julia has. It is an "additive" comparison.
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You need to be a little careful with this. You will often see wording such as "... <em>times more</em> than ...", in which case it is a multiplicative comparison. (I would prefer the multiplicative comparison wording to be "... times as many as ...", so that "more" is reserved for additive comparisons. Alas, not in this lifetime.)