Help please!

0<x<1, 2x<y<3x, xy/5<z<5xy

You are told x is between 0 and 1

I seperated the rest into 4 different constraints

2x<y

y>2x

The smallest 2x can be (not quite) is 0 so y>0

y<3x

The limit for 3x is 3 so y has to be smaller than 3

0<y<3

xy/5<z

z>xy/5

the lower limit for x is 0 and the lower limit for y is 0 so 

xy>0

xy/5>0

z>0

z<5xy

The upper limit of xy is 1*3=3

so the upper limit of 5xy is 15

z<15

0<z<15

limit constraints

0<x<1

0<y<3

0<z<15