Jawabanmu

2014-06-03T19:02:54+07:00
5. K = 2 ( p + l )
240 cm = 2 ( 7x + 5x )
240 cm = 24 x
x = 240cm  : 24
x = 10cm
l = 5x = 5.10 = 50 cm
2014-06-03T19:14:53+07:00
5.  \frac{5}{2(7+5)} x 240
     = 50
6. 4 (x +3) = 2(2x - 3 + x + 1)
    4x + 12 = 4x - 6 + 2x + 2
     4x - 4x - 2x = -6 +2 - 12
         -2x    =  -8
           x    =  \frac{-8}{-2}
           x    = 4
1 5 1