1)643-(581-b)=292
643 – 581 + b = 292
b = 292 + 581 – 643
b = 230
2) 987-(x+364)=519
987 – x – 364 = 519
– x = 519 + 364 – 987
-x = -104
x = 104
3) 3128-(m+425)=1509
3128 – m – 425 = 1509
– m = 1509 + 425 – 3128
-m = -1194
m = 1194
1)643-(581-b)=292
643 – 581 + b = 292
b = 292 + 581 – 643
b = 230
2) 987-(x+364)=519
987 – x – 364 = 519
– x = 519 + 364 – 987
-x = -104
x = 104
3) 3128-(m+425)=1509
3128 – m – 425 = 1509
– m = 1509 + 425 – 3128
-m = -1194
m = 1194