A tree had 1000 leaves before the onset of the dry season, when it sheds all its leaves. In the first week of the dry season, the tree shed 2/5 of the leaves. In the second week, it shed 40% of the remaining leaves.  In the third week, the tree shed 3/4 times as many leaves as it shed on the second week. Calculate the number of leaves the tree hadn't shed by the third week.
In the first week, the tree shed 2/5*1000 = <<2/5*1000=400>>400 leaves.
The number of leaves remaining on the tree at the end of the first week is 1000-400 = <<1000-400=600>>600
In the second week, the tree shed 40/100*600 = <<40/100*600=240>>240 leaves.
The number of leaves remaining on the tree is 600-240 = <<600-240=360>>360
The third week the tree shed 3/4 of its leaves, a total of 3/4*360 = <<3/4*360=270>>270 leaves.
The number of leaves remaining on the tree is 360-270 = <<360-270=90>>90 leaves.
#### 90