Question

2+7=34, 8+9=18, 6+3=76, 5+7=?

Answer 1

2 + 7 = (2 x 10) + (2 x 7) = 34

8 + 9 = (9 x 10) - (9 x 8) = 18

6 + 3 = (6 x 10) + (6 x 3) = 78

so,   5 +7 = ( 7 x 10) - (7 x 5) = 35