Answer:
7x/12
Step-by-step explanation:
Let her entire allowance be represented by 'x'
She spent 5/8 of 2/3 of her allowance on magazines.
= 5/8×2/3
= 10/24
= 5/12
That 5/12 of 'x'
5/12x
Since her total allowance is x
She will be left with = x - 5/12x
x/1 - 5/12x
12x-5x/12x
= 7x/12
Hence she will be left with 7x/12
12.
12x3 is already 36, more than 30..
I am using the laws:
1)

2)

3)

an x is a base - the law is valid if the bases are the same number!
The solution in attachment :)
-6/7p+1/7 um Idk what you wanted me to do but I added -4/7p with -2/7p
13, 21, 34 are the next three numbers