Question

51+(x+23)+26=100
49+x+21+230=2312
1+2+3+4+x+6+7+8+9=550

Answer 1

1.
51+(x+23)+26=100
x=100-51-23-26
x=0
2.
49+x+21+230=2312
x=2312-49-230-21
x=2012
3.
1+2+3+4+x+6+7+8+9=550
x=550-1-2-3-4-6-7-8-9
x=510