Question

Steve bought a total of 6 packages of pens, and each package contained either 3 or 7 pens. If exactly 4 of the packages Steve bought a package that contained 7 pens, how many pens did Steve buy?
A) 21
B) 28
C) 30
D) 34
E) 42

Answer 1

The answer is D, 34

If 4 of the packages contain 7 pens, that means there, 28 pens are total.

Because they contained either 3 or 7 pens, I would assume the remaining 2 packages of 6 total that Steve had bought would have to have 3 pens. 

3*2 is equal to 6

28 + 6 = 34

Answer 2

The answer is D.
Calculate how many pens he bought for only the bags with 7 pens each. You get 28.
Next, since you know there are 2 bags left that each must have 3 pens only, calculate how many pens he bought in only those 2 bags. You get 6.
Add the 2 values. 28+6 is 34, so your answer is choice D.