a) (4/x )*147=84=>( 4*147)/x=84
588/x=84=>84*x=588
x=588:84=>x=7
b) (9/x)*803=657=>
(9*803)/x=657=>
7227/x=657=>657*x=7227
x=7227:657=>x=11
c) (25/x)144=150
(25*144)/x=150
3600/x=150=> 150*x=3600
x=3600:150=>x=24
d) (99/x)*4500=495
( 99*4500)/x=495
445 500/x=495
495*x=445 500
x=445 500:495
x=900