We have a question: Miley bought two cellphones for her parents. Each cellphone costs $800 but, since she is buying two units, she will receive a 5% discount for the total cost. How much did Miley pay?
And an answer: 1520
So how you got the answer?
Two cellphones cost $800 x 2 = $1600. The 5% discount amounts to $1600 x 5 / 100 = $80. So Miley paid $1600 - $80 = $1520.

We have a question: There are 10 rows of 15 chairs set up for the award ceremony. The first row is reserved for the awardees while the second and third rows are for the administrators and teachers. The last two rows are then reserved for the parents and the rest of the rows are for the students. If only 4/5 of the seats reserved for the students are occupied, how many vacant seats from the students can be given to the parents?
And an answer: 15
So how you got the answer?
There are 1 + 2 + 2 = 5 rows that are not reserved for the students. Hence, 10 - 5 = 5 rows are reserved for the students. That is equal to 5 x 15 = 75 seats. But only 75 x 4 / 5 = 60 seats are occupied by the students. Therefore, 75 - 60 = 15 seats can be given to the parents.

We have a question: Three adults whose average weight is 140 pounds went first in the elevator. Two children whose average weight is 64 pounds also went inside. If an elevator sign reads “Maximum weight 600 pounds.", what is the maximum weight of the next person to get in the elevator so that it will not be overloaded?
And an answer: 52
So how you got the answer?
The sum of the weights of the three adults is 140 x 3 = 420 pounds. The sum of the weight of the two children is 64 x 2 = 128 pounds. So the total weight of the 5 people who are in the elevator is 420 + 128 = 548 pounds. This would mean that the next person's weight must not exceed 600 - 548 = 52 pounds.