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Algebra Difficulty 2.9 Junior Find the answer

(1+11+21+31+41)+(9+19+29+39+49)=(1+11+21+31+41)+(9+19+29+39+49)=

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Solution

We make use of the associative and commutative properties of addition to rearrange the sum as
(1+49)+(11+39)+(21+29)+(31+19)+(41+9)=50+50+50+50+50=250⟹E\begin{align*} (1+49)+(11+39)+(21+29)+(31+19)+(41+9) &= 50+50+50+50+50 \\ &= 250 \Longrightarrow \boxed{\text{E}} \end{align*}

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.