A sample of radioactive element follows the law of exponential decay. if there are 50g of the element at noon 30g at 3:00 pm that same day then how many grams will there be at 9:00 pm that same day?​

Aswimming pool has an input pump for filling the pool and an output pump for emptying the pool. the input pump can fill the pool in 3 hours, and the output pump can drain the pool in 5 hours. as you go to bed, the pool is full, but a neighbor’s kid turns on the output pump. at midnight, you awake to find the pool half empty. immediately, you turn on the input pump, but you are sleepy and forget to turn off the output pump. at what time will the pool become full?

Solve with work both bert and ernie received an increase in their weekly salaries. bert's salary increased from $520 to $520. ernie's salary went from $580 to $645. find the percent of increase for each salary. what was the larger of the two percents ?

Jenisey has $24 to spend on seven pencils. after buying them she had $10. how much did each pencil cost.?