Jack and jim sign up with an online music store. jack chooses 15 downloads for $19.75, and jim chooses 40 downloads for $43.50. both amounts include a one-time registration fee, which is the same for each account, plus the fee for the number of downloads. what is the registration fee, and what is the cost of each download?

a. the registration fee is $5.50, and the cost per download is $0.95.

b. the registration fee is $3.50, and the cost per download is $1.00.

c. the registration fee is $2.50, and the cost per download is $0.85.

d. the registration fee is $4.75, and the cost per download is $1.00.

Thus, the correct answer is option A

Explanation-

Let the cost of each n load be "x" while the one time registration fee be "y"

Jack chooses downloads and the total expenditure of him including tex]15\\[/tex] downloads and one time registration fee "y" is $

This can be represented as

Expenditure by Jack

...................Eq (A)

Similarly , Jim  chooses downloads and the total expenditure of him including tex]40\\[/tex] downloads and one time registration fee "y" is $ .

This can be represented as

Expenditure by Jim

...................Eq (B)

From equation A  we get

Substituting this values of y in equation (B) ,we get

Substituting this value of x in equation A, we get

Thus, the correct answer is option A

links? do you have a link? i don't see anything?

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.