Monday through Friday is 5 days.
Multiply the cost of lunch by number of days:
3.25 x 5 = $16.25
Subtract the total he spent on lunch from what he started with for money:
20 - 16.25 = 3.75
He had $3.75 left.
Add all the numbers in the ratio together to get 18 then divide 180 by 18 to equal 10. then times that by each individual number in the ratio. so the answer is 40:50:90
You can find the rate of change by taking it's derivative.
Answer:
a) 
b) 6.84 million
c) 2028.52
d) 47 years
Step-by-step explanation:
a)Here we know standard exponential growth rate is

In this put t=0 and a(t)=6.27 million
thus we get a = 6.27 million
now 
this is equal to(in 2012)=
b)Put t = 6
we get

=6.84 million
c) 
take log both sides
we get 16.52 years
d) 
take log both sides we get 47 years to get double the current population.
[ 1 ] Given
[ 2 ] Exterior Sides Opposite Rays
[ 3 ] Definition of Supplementary angles
[ 4 ] First substitution
[ 5 ] Subtraction Property of Equality
[ 6 ] Second Substitution
[ 7 ] If corrsp. equal, the lines ||