Question 1025835
Let S1=10-cent stamps and S2=15-cent stamps

If 40 stamps cost $5.40, then 1 stamp cost 0.135

Using the method of alligation,

0.135-0.10=0.035

0.15-0.135=0.015

So that S1/S2=0.015/0.035

Then S1=(0.015/0.05)(40)=12 10-cent stamps (Answer)

S2=40-12=28 15-cent stamps (Answer)