Posted by Mayyday on .
The number of S's stamps is 30% of D's stamps. The number of D's stamps is 40% of B's stamps. If they have 608 stamps, how many stamps does D have?
(i need a model method to answer this)

Maths Pri 5 
Damon,
s = .3 d
d = .4 b so s = .12 b
s + d + b = 608
.12 b + .4 b + b = 608
1.52 b = 608
b = 400
d = .4 b = 160