Currently about 9 in 10 people own a cell phone in the us. if there are 428 people on an airplane, approximately how many of them own a cell phone and need to turn it off. 375 380 385 390

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.

Solve this problem! extra ! 3025/5.5 = a/90.75