Question: If Pam is currently twice as young as Rena is, and in 10 years Rena will be 5 years older than her, how old is Pam now?
Answer with step-by-step thinking: If Rena will be 5 years older than Pam in 10 years, this means they have a 5 year age gap. Therefore, to be twice Pam's age, Rena would have to be 5 * 2 = 10 years old. This means that Pam is currently 10 - 5 = 5 years old.
So the answer is 5.

Question: Leila and her friends want to rent a car for their one-day trip that is 150 kilometers long each way. The first option for a car rental costs $50 a day, excluding gasoline. The second option costs $90 a day including gasoline. A liter of gasoline can cover 15 kilometers and costs $0.90 per liter. Their car rental will need to carry them to and from their destination. How much will they save if they will choose the first option rather than the second one?
Answer with step-by-step thinking: Leila and her friends will travel a total distance of 150 x 2 = 300 kilometers back - and - forth. They will need 300 / 15 = 20 liters of gasoline for this trip. So, they will pay $0.90 x 20 = $18 for the gasoline. Thus, the first option will costs them $50 + $18 = $68. Therefore, they can save $90 - $68 = $22 if they choose the first option.
So the answer is 22.

Question: At a certain school, 2/3 of the population are females. One-tenth of the males are foreign students. If the school has 300 students, how many students are non-foreign male students?
Answer with step-by-step thinking:
There are 300 x 2 / 3 = 200 females in the school. So, 300 - 200 = 100 are males. Out of the 100 males, 100 x 1 / 10 = 10 are male foreign students. Thus, there are 100 - 10 = 90 non - foreign male students.
So the answer is 90.