The half-life of helium-5 is 7.6 × 10-22 seconds, and the half-life of helium-9 is 7 × 10-21 seconds. approximately how many times greater is the half-life of helium-9 than that of helium-5?

Solve the equation using the given values: x= -2.5; y= -7.51. 2xy + 2x²

Andy has $310 in his account. each week, w, he withdraws $30 for his expenses. which expression could be used if he wanted to find out how much money he had left after 8 weeks?

Which problem would you use the following proportion to solve for? 24/x = 40/100 a. what is 40% of 24? b. what percent is 24 of 40? c. twenty-four is 40% of what number? d. forty percent of 24 is what number?