928-(31+x)=128
31+x=928-128
31+x=800
x=800-31
x=769
928-(31+x)=128
31+x=928-128
31+x=900
x=800-31
x=769
928 - ( 31 + x ) = 128
31 + x = 928 - 128
31 + x = 800
x = 800 - 31
x = 769
928-(31+x)=128
31+x=928-128
31+x=800
x=800-31
x=769
928-(31+x)=128
=> 31 + x = 928 - 128
=> 31 + x = 800
=> x = 800 - 31
=> x = 769
31+x=928-128
31+x=800
x=800-31
x=769
928-(31+x)=128
31+x=928-128
31+x=800
x=800-31
x=769