**9347**

You need to multiply the digits of the first number with the reverse of the digits in second number as shown below for the first equation;

8 x 2 = 16

6 x 4 = 24

3 x 5 = 15

8 x 7 = 56

Now take the first digit of all the results and hence we get;

8638 + 7542 = 1215

Similarly for the second equation we get;

5 x 8 = 40

5 x 6 = 30

8 x 4 = 32

9 x 2 = 18

After taking the first digits we get;

5589 + 2468 = 4331

Then;

1357 + 1919 = 9347

1 x 9 = 9

3 x 1 = 3

5 x 9 = 45

7 x 1 = 7

**Answer = 9347**