It is: 1318 plus 19 = 1337
18 and 19
17, 18, and 19
18, 19, 20
They are: -18+(-19) = -37
It is: 1318 plus 19 = 1337
18 and 19
37 - at least it was when I went to school !
17, 18, and 19
54
18, 19, 20
They are: -18+(-19) = -37
18, 19, 20
41 - 9 = 32
17+18+19
57
18+19 = 37