True or false ? why and why not ?

7a + 4 - 2a is equivalent to 7a + -2a + 4

Gigi earned $65 for 5 hours of gardening. she earned $90 for 9 hours of office work. which statement correctly compares gigi’s earning per hour for gardening and office work? she earned $3 more per hour for office work than for gardening. she earned $4 more per hour for office work than for gardening. she earned $3 more per hour for gardening than for office work. she earned $4 more per hour for gardening than for office work.