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MYTS 2019 — Grade 7 — Round 1 Question 5

MYTS · MYTS 2019 — Grade 7 — Round 1

Question 5

Ten numbers $a_1,a_2,\ldots,a_{10}$ satisfy

$$\frac{a_1-1}{10}=\frac{a_2-2}{9}=\frac{a_3-3}{8}=\cdots=\frac{a_{10}-10}{1},\qquad a_1+a_2=41.$$

Find $S=a_1-a_2+a_3-a_4+\cdots+a_9-a_{10}$.

Question illustration