The increase of the radius is a linear increase since we have the constant rate of 0.07 inches per second
The equation for a linear growth/decay is given by the form

where

is the rate of increase and

is the value of

when

We have

when
So the equation is 
The length of the radius when

seconds is


inches
C = 16h
This is the basic set up of a cost function which is a direct correlation.
43 tens = 43 * 10 = 430
3 tens = 3 * 10 = 30
430 x 30 = 12900 tens
12900/100 = 129 hundreds <===
Answer:
36 students speak both english and french
14 students speak only english
1/2 because it's 2 times smaller