40 - 16 = 24
-90 (when you add a negative you simply subtract so -40-50 is -90)
(7/8) - (3/5) = (35/40) - (24/40) = 11/40 = 0.275
It is simply: 24 times 40 = 960 square feet
Since 1000 is a multiple of 40... the next lowest multiple is 960. Therefore you simply subtract 40 !
20
24% of 40= 24% * 40= 0.24 * 40= 9.6
7 times 6 is 42. If you subtract two, you get 42-2= 40.
30
28
55
24-40 = -16