Jawabanmu

2014-03-16T14:14:42+07:00
90 : (20+16) =
       ----------
          2
90 : 36 =
      -----
        2
90 : 18 = 5
  
2014-03-16T14:19:20+07:00
L = 90 CM2
isi sejajar = 16 &20 cm
t =?
L =  \frac{a+b}{2} * t
90 = \frac{20+16}{2} *t
     =[tex] \frac{36}{2}*t
     = 18 *t
t =90/18
  = 5 cm