Question

175+...-250=375
...+110-350=240
630+...-150=650
780-...-100=630

Answer 1

1)175+х-250=375
х=375+250-175
х=450
2)х+110-350=240
х=240-110+350
х=480 
3)630+х-150=650 
х=650-630+150
х=170
4)780-х-110=630 
-х=630-780+110
х=40