Paul has 2/3 as many postcards as Shawn . The number of postcards Shawn has is 3/5 of the number of postcards Tim has. If the three boys have 280 postcards altogether,how many more postcards does Tim have than Paul ?
+876 Paul has 2/3 as many postcards as Shawn . The number of postcards Shawn has is 3/5 of the number of postcards Tim has. If the three boys have 280 postcards altogether,how many more postcards does Tim have than Paul ?
$p = \frac{2}{3}s$
$s = \frac{3}{5}t$
$p+s+t=280$
$p=\frac{2}{5}t$
$2t=280$
$t=140$
$(1-\frac{2}{5})t = \frac{3}{5} \cdot 140 = 3 \cdot 28 = \boxed{84}$
