Mathematics

Tomcat

10 April, 22:29

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