Part A:
answer- $1.80
(20% of $1.50 is .30, so 1.50+.30=1.80)
Part B:
September=$540 ( 1.50 times 900 is 1,350, 40% of 1,350 is 540)
October=$504 ( 1.80 times 700 is 1,260, 40% of 1,260 is 504)
answer=they earned more money in September; $36 more
(540-504=36)
Hope this helped!