Originally posted by knptmug at 2005-4-20 09:47 PM:$ U: r0 A- J2 k5 R' L! G
set small watermelon: x, middle watermelon y and big watermeton z* G) i# [' r' K0 Q8 F+ {' v* {& a
9 a) @) \6 N- _6 x3 `& T
two simultaneous equations are set up: % g" f! z+ \. B/ b! L0.5x+2y+5z=50 (1)* O5 h% C, u, n/ _% ^+ ]) r- Z
x+y+z=50 (2)' w) ?% r8 M6 P4 u( D
Equation(1) means that the total amount paid is equal t ...