Why are 36: 8,9: 3,72: 16 equivalent to 18: 4

They all can be divided by the same number like 36:8 divided by 2 is 18:4 
u could also set it up like this : 36  18
                                              _=  _
                                              8    4
replace one of the numbers with an X i used 4  now multiply 8 times 18 and divide it by 36 and it will equal 4 which means they are  equivalent

Where the white dots are is where your points should be plotted.a translation is simply just moving something from one place to another. in this case, you would move each plot point of the original shape 2 units up, and 5 units to the left.