1. 2+3=5

Question

Two plus three is five.
Two plus three are five.
Two plus three makes five.
Two plus three make five.
Two and three is five.
Two and three makes five.
Two and three are five.
Two and three make five.
(Are all grammatical?)

2. 3-2=1
Three minus two is one.
Three minus two are one.
Three minus two makes one.
Three minus two make one.
Three subtracted from two is one.
Three subtracted by two is one.
(Are all correct?)

Answer 1

http://grammar.ccc.commnet.edu/grammar/sv_agr.htm

See #11.

"Sums and products of mathematical processes are expressed as singular and require singular verbs."

Therefore ...

1. 2+3=5
Two plus three is five. yes
Two plus three are five. no
Two plus three makes five. yes
Two plus three make five. no
Two and three is five. yes
Two and three makes five. yes
Two and three are five. no
Two and three make five. no
(Are all grammatical?)

Now, what will you say about the second set you posted?

Answer 2

Since plus and minus are prepositions, we use a singular verb with them.

These are correct:

Two plus three is five.
Two plus three makes five.
Three minus two is one.
Three minus two makes one.

But and is a conjunction so we use a plural verb with it.

These are correct:

Two and three are five.
Two and three make five.

These are also correct:

Three subtracted from two is one.
Three subtracted by two is one.