I dont understand number 2, but I can help with number 3.
3. 8*8*8= 512 - 1 = 511 / 7 = 73
(sorry if its wrong, im taking algebra I im in 8th.)
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Well 52 divided by 8 is 6.2 so..
Ok. So first plug in the X.
8[1/8(4)] + 6(4)
Then do the work
8(1/2) + 24
4+24
28
The answer is 28