A1 = 35x+25
Good guys = 40x
35x+25 = 40x
subtract 3x x from each side
25 = 5x
divide each side by 5
x = 25/5 = 5
so 5 hours they would be the same cost, anything over 5 hours and A1 would be better
so X>5 for A1 to be the better price
Answer:
Mostly correct
For Q3, you are doing great, you remembered that negative numbers can happen if the exponent is an odd number.
For Q4, I think you were confused with the fractions,
4(i)

4(ii) is also wrong but I'll let you try to fix it yourself following what I given you for 4(i). You should get 1/64
Hope this helps!
You can solve this problem by applying the proccedure below:
You have:
a) 18/21=2/3
18x3/21x2
36≠42 (2/3 is not proportinal to 18/21).
b)18/21=30/35
18x35/21x30
630=630 (30/35 is proportional to 18/21)
c)18/21=36/48
18x48/21x36
864≠756 (36/48<span> is</span><span> not proportinal to 18/21)
</span>
d)18/21=1/3
18x3/21x1
54≠21 (<span> 1/3 is</span><span> not proportinal to 18/21)
</span>
Therefore, you can conclude that the correct option is: B.30/35