Bonjour,
Dédé se note D,
Francis F,
Boudin B.
[tex] \left \lbrace \begin{array}{r @ { =}l}D+B & 140 \ (1) \\D+F & 145\ (2) \\F+D & 35 \ (3) \end{array} \right \\\\\\
\left \lbrace \begin{array}{r @ { =}l} \dfrac{(1)+(2)+(3)}{2} \ D+B+F & 160 \ (4) \\ (4)-(1) \ F & 20\ (5) \\ (4)-(2) \ B & 15 \ (6) \\ (4)-(3) \ D & 125 \ (7)\end{array} \right \\\\
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