How would i solve this porportion problem. #20

#20  16/36 = 4/d 4 x 36 = 144/16= 9   d=9                                                                                                                          #24      144/40 = x/5  144 x 5/40=18 x=18                                                                                                                         

Well you would cross multiple 36x4 which is 144 then you would divide that by 16 which would be 9 and 9 is d