问题:

试题 题型:未知 难度等级:

设数列{an},{bn}都是等差数列,若a1+b1=7,a3+b3=21,则a5+b5=______.

设数列{an},{bn}都是等差数列,若a1+b1=7,a3+b3=21,则a5+b5=______.

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