It is best to use the discount first because the more value, higher percent.
Discount First:
4.00*.5 = $2.00 TOTAL
$2.00-$1.00 = $1.00 GRAND TOTAL
Discount After:
4.00-1 = $3.00 TOTAL
3*.5 = $1.50 GRAND TOTAL
You would save 50 cents
Let the number of pages read on day 1 be = x
Then on day 2 he read twice the pages from day one, it is = 2x
On 3rd day he read 6 pages less than 1st day, it is = x-6
Total pages are = 458
The equation becomes: 
So on the third day, Aiden read 
pages.
Let's call the two numbers a and b. So we know that the difference of the two numbers is 36:
a - b = 36
And we know that their sum is 286:
a + b = 286
We can use either of these equations to solve for one of the variables in terms of the other variable. Let's use the first and solve for a:
a - b = 36
a = 36 + b
Now we plug this into the other equation and solve for b there:
(36 + b) + b = 286
36 + 2b = 286
2b = 250
b = 125
