The required diminished expression is 6c+d.
Given
Expression; a - 2b + 3c diminished by a - 2b - 3c + d.
To diminish the expression firstly combine like terms after then simplify the equation.
Therefore,
The expression is diminished by;
[tex]\rm =a - 2b + 3c-(a - 2b - 3c+ d)\\\\=(a-a)-(2b-2b)+(3c+3c)+d\\\\= 6c+d[/tex]
Hence, the required diminished expression is 6c+d.
To know more about Expression click the link given below.
https://brainly.com/question/1553964