1) 135+241-332 = 376-332 = 44
2) 678 - R = 654
R = 678 - 654
R = 24
3) 298-287+24 = 11+24 = 35
4) c + 230 = 256
c = 256 - 230
c = 26
5) 4 × 5 = 20
20 + 26 = 46
6) 457-420+5•6 = 37+30 = 67
7) 549+230-710 = 779-710 = 69
8) 234 - 224 = 10
10 + 69 = 79
9) 425 + x = 499
x = 499 - 425
x = 74
10) 555 - (200 + 300) = 555 - 500 = 55