Match two cells to place a value in Excel -

if have function

right / left

a     b - 1 b     c - 2 d     4 - 3 e     - 4     2 - 5 4     d - 6 2     e - 7 

how can place value of - x right side? e.g. e has 7 on left. moving 7 right side

a     b - 1 b-1     c - 2 d-6     4 - 3 e-7     - 4 i-4     2 - 5 4     d - 6 2     e - 7 

i've tried using match function , index not wanted. thank much.