Question 444835
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Hi
Maximum heart rate R is R=220- A, where A is the person’s age
and R is the heart rate in beats per minute.
R(20) = 220-20 = 200
R(70) = 220-70 = 150
 Ordered pairs 
(70,150) and 
(20,200)   m = -50/50 = -1   |Using the point-slope formula, {{{m =(y[2] - y[1])/(x[2] - x[1])}}}
Using the standard slope-intercept form for an equation of a line y = mx + b 
 where m is the slope and b the y-intercept.  
  As stated: R = -A + 220
Plot (70,150) and (20,200)and connect with line.
Graph says as age increases, that Maximum heart rate number decreases
{{{drawing(300,300,   -250,250,-250,250,  grid(1),
circle(70, 150,6.0),
circle(20, 200,6.0),
graph( 300, 300, -250,250,-250,250,0,-x+220  ))}}}