40 + 90 = 130
The sum of the equation - 990 + 880 +90 +790 +690 + 40, is found as follows;990 + 880 +90 +790 +690 + 40= (990 + 880) + (90 +790) + (690 + 40)= ( 1870 ) + (880 ) + ( 730 )= 3480Answer = 3480
90
The sum of the equation - 990 + 880+40 +90 +790 +690, is found as follows;990 + 880 +40 +90 +790 +690= (990 + 880) + (40 +90) + (790 + 690)= ( 1870 ) + ( 130 ) + ( 1480 )= 3480Answer = 3480
638.
90.
-90 (when you add a negative you simply subtract so -40-50 is -90)
-25052
329
130 84+6=90 46-6=40 90+40=130
90.
10 plus 20 plus 30plus 40 plus 50 equals 150 because 50 plus 40 equals 90 plus 30 =120+20= 140 then + 10 = 150
This is so simple - my 5-year-old nephew answered it... 270 !