Elena purchased Brand X pens for $5.00 apiece and brand Y for $2.80 apiece.
Elena purchased Brand X pens for $5.00 apiece and brand Y for $2.80 apiece. If Elena purchased a total of 12 of these pens for $42.00, how many brand X pens did she purchase?
Answer/Solution
6
Steps/Work
4x+2.8y=42 --> multiply by 2.5 (to get the integers) --> 10x+7y=105 --> only one positive integers solutions x=6 and y=5 (how to solve: 7y must have the last digit of 5 in order the last digit of the sum to be 5).
Answer: C.
Answer: C.