Answer: 
Step-by-step explanation:
Let be "x" the time in minutes a 150-pound person must walk at 4 mph to use at least 190 calories.
The amount of calories that a 150-pound person uses in 1 minute when walking at a speed of 4 mph is:

Therefore, knowing this, we can write the following proportion:

Finally, we must solve for "x" in order to find its value.
Multiplying both sides of the equation by 190, we get this result:

Remember: 50% means 1/2. So, if 18 is 50%, or 1/2, of a number, the number must be double 18.
18 x 2 = 36
18 is 50% of 36.
Calories used = Activity level*Weight*Duration
Activity level at 8 min/mile = 0.22 calories per minute
Weight = 180/2.2 = 81.81 kg
Duration = 8 minutes
Substituting;
Calories used = 0.22*81.81*8 = 144 calories
k = 12
cancel out the r on both sides
then divide -144 by -12.
you get 12.
Answer:
242.975609756
Step-by-step explanation: