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?
a. She earned $3 more per hour for office work than for gardening.
b. She earned $4 more per hour for office work than for gardening.
c. She earned $3 more per hour for gardening than for office work.
d. She earned $4 more per hour for gardening than for office work.