Sum = 79*(79+1)/2 = 79*80/2 = 3160
79 + 79 = 158 / 2 = 79.
79, -79
1,042
79 + 79 = 158
a + 79
79 + 79 = 158
9h + 2 < - 79 9h < - 81 h < - 9
9h + 2 = -79 9h = -81 h = -81/9 h = -9
42 + 79 = 121 (40+70) + (2+9) = = 110 + 11 = 121
79
The solution to 79 plus 39 is 118. The solution to 79 minus 39 is 40.