Medical researchers have determined that for exercise to be beneficial, a person’s desirable heart rate, R, in beats per minute, can be approximated by the formulas


R=143-0.65a for women

R=165-0.75a for men,


where a represents the person’s age. If the desirable heart rate for a man is 135 beats per minute, how old is he?

a.22.5 years old

b.40 years old

c.45 years old

d.42.5 years old




Evaluate the function

f(x)=1/2x+3


for f(4).

A5
B9
C11
D14