Urgent! johnny is considering two different
cell phone companies. company a will charge him
$50 a month plus $0.15 a minute. company v will
only charge him $35 a month but a $0.20 per
minute usage fee. how many minutes of usage will
make his total cost the same for each company?
show equation and work

Which recursive formula can be used to determine the total amount of money earned in any year based on the amount earned in the previous year? f(n+1)=f(n)+5

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?