Detailed explanation of number reasoning 78,38,18,10,4, () 78,38,18,10,4,() Four alternative answers 2,1,4,3

Detailed explanation of number reasoning 78,38,18,10,4, () 78,38,18,10,4,() Four alternative answers 2,1,4,3

Here is the correct answer
(78+18)*4-38*10=4