From FiveThirtyEight.com, as of March 29, 2016:

"Trump’s favorable rating among the general electorate is, on average, 30 percent. His unfavorable rating is a sky-high 63 percent. In other words, a lot more people dislike Trump than like him. The American public was more evenly split on Reagan at a comparable point in the 1980 campaign. According to an April 1980 Cambridge Reports survey, 39 percent of Americans had a favorable view of Reagan, and 44 percent had an unfavorable view. Reagan’s net favorability rating was 28 percentage points higher than Trump’s is."

Also, that a person is said to a "favorability" rating of, say, "30%" does not necessarily mean (and almost certainly doesn't mean) that that person's "unfavorability" rating will be "70%." Invariably, a non-de minimis number of people polled will have neither a favorable nor an unfavorable view of a given person.