assuming that you mean to ask . . . "What is 7.4 as a fraction in simplest form?"
7.4 = 7 and 4/10
4/10 can be reduced to 2/5
7 represents = (7*5)/5 = 35/5
so . . 7 + 4/10 = 35/5 + 2/5 = 37/5 (improper fraction in simplest form)
or
. . . . 7 + 4/10 = 7 2/5 (mixed fraction in simplest form)