I'm in 6th grade MEGSSS and don't understand all this stuff about neutral numbers and sets. In particular:
Let * be an operation on W, defined as follows:
for all a, b in W, a * b = a
i) 3 * (7 * 9) =
ii) (3 * 7) * 9 =
iii) 8 up arrow (15 * 2) =
iv) 8 up arrow (2 * 15) =
Note: I had to write out "up arrow" because there isn't an up arrow notation on my keyboard. Also, for those looking at this, the * does not mean "times" or "x" - it meas "set." Thanks.