Question 32808
Let Amy's stamps be x
Let Robin's stamps be y
She loses 10 -->x-10
Other gains 10 -->y+10
4(y+10)=x-10
4y+40=x-10
x=4y+50 (subsitution)


She loses 20 -->x-20
other gains 20 -->y+20
3(y+20)=x-20
3y+60=x-20
3y+60=4y+50-20
y=30


x=4(30)+50
x=170
Hence, Amy has 170 stamps, and Robin has 30 stamps.
Paul.