The logic followed in the given equations are as follows;
R1 x R2 + (R2 – 1) = R3
So if we apply this in the given table, you will see;
3 x 2 + (2 – 1) = 6 + 1 = 7
Similarly for other rows we can solve the equation as;
5 x 4 + (4 – 1) = 20 + 3 = 23
7 x 6 + (6 – 1) = 42 + 5 = 47
9 x 8 + (8 – 1) = 72 + 7 = 79
Therefore we can find the missing number as;
10 x 9 + (9 – 1) = 90 + 8 = 98
Answer = 98