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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 minus 0.65 a for women r = 165 minus 0.75 a for men, where a represents the person’s age. if the desirable heart rate for a woman is 130 beats per minute, how old is she? a. 84 years old b. 57 years old c. 37 years old d. 20 years old



Answer :

She is 20 years old when her heart rate is 130 beats per minute.

What are Linear Equation?

Linear equation are those in which power is 1 or maximum degree is 1. For example: x + y = 3 here the maximum degree is 1.

Linear equation can be in:

One variable, Two variable and might be N- number of variable.

Here, We have given Two Linear equations:

1. For Men: r = 165 - 0.75(a)

2. For Women: r = 143 - 0.65(a)

where 'a' represents the person's age.

Now, Here we have given Women's heart rate, r = 130 beats per minute.

using second equation,

r = 143 - 0.65(a)

130 = 143 - 0.65(a)

0.65(a) = 143 - 130

0.65 (a) = 13

a = 13/0.65

a = 20 years

Hence,

She is 20 years old when her heart rate is 130 beats per minute.

Learn more about " Linear equation " from here: https://brainly.com/question/11897796

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