Aside from online polls being a joke, this one from Purple Strategies for Bloomberg saying people making between $30,000 and $75,000 are "working class" is as phony as they get:
“If he [Trump] can’t improve his performance among these working-class voters, he may need to build a more conventional Republican coalition to win,” said pollster Doug Usher.
Those are middle class people, not working class, and numbered about 54 million in 2014.
Working class people with whom Trump is wildly popular make up to $30,000 and numbered about 81 million in 2014.
This "poll" is trying to shape perceptions, not measure them.