Voltage divider with a potentiometer
Assuming this is a homework question and not real-world- you know the range of voltage adjustment, which defines the voltage across VR2's element, and thus the current through VR2.
Once you know the current through VR2 you know the current through R3 and R1 since they are all in series. You then can easily calculate the value of R3 to get the required voltage at the low end of the element and the value of R1 to establish that current.
In the real world, if you wanted guaranteed range of adjustment it would be more complicated and in particular because the tolerance (and tempco) of pot elements tends to be poor in comparison to resistors. So you'd either use lower values for R1/R3 to increase the range or add another resistor to mitigate the effects of VR2.