Summing fractions the wrong way

Algebra Level 2

You should know that

$\frac{a}{b} + \frac{c}{d} \ne \frac{a+c}{b+d}.$

However, if $$a, b, c, d$$ are positive integers that satisfy $$\frac{a}{b} < \frac{c}{d},$$ what can we say about $$\frac{a+c}{b+d} ?$$

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