340 × .2 = 68
68 page decrease
340 - 68 = 272
272 pages left
The correct answer is Choice A.
This is an example of an exponential equation, so we need the formula

.
The a value is the starting value of 100. The b value must be a decimal lower than 1 because it is decreases.
If you substitute in 8 for x, you will see that the output is about 50 (half of 100).
So all u have to do is just add $1.28 and $0.54
Nobody goes around with lists of greatest common factors in their head.
When we need to know one, we grab the nearest pencil and work it out.
The factors of 40 are 1, 2, 4, 5, 8, 10, 20, and 40 .
The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36 .
The common factors of 35 and 40 are 1, 2, and 4 .
The biggest one is 4 .