From voltage plot to diode circuit
It is easy to satisfy the denominator of the voltage divider ratio R1/(R1+R2) which is the tangent or the opposite over adjacent in geometry.

This design spec requires a +ve only output for a bipolar input and this is called a fullwave (FW) rectifier. 

But the voltage ratio is created by splitting open the +ve side of the FW bridge and inserting any R value such that the ratio of load to the sum of load + source = the slopes +2/3 and +2/5 for the negative input.



Teachers often not tell you why silicon diodes are 0.7V.  This is typical for a small rated current and depends on power rating of diode.   Thus there is not standard value of current for 0.7V.  But since the current is low at 0.6 V, the internal electrode+semi junction "bulk"  resistance, Rs does not influence the threshold voltage much so remember this.  1mA Silicon diode= 0.6V (same as Vbe)  It might be 50mA to 1A get 0.7V depending on power rating so when using kiliohm resistors , assume the 0.6V @ 1mA instead.

In my diagram I put scope traces for the top  diode V(t) above I(t) which shows a max of 623mV @ 29mA max which used even smaller resistors. I created the XY plot by creating Vin then Vout then "combine" then  choose XY. You can rotate the plot by swapping part ends with a right mouse click.