A company makes t-shirts and their research shows that that price and demand are related linearly: p = m x + b . They know that in order to sell 5 shirts they need to set the price at $50, and in order to sell 10 shirts they need to set the price at $40. Find the linear equation relating price to demand.

The linear equation relating price to demand is Q=-0.5*P + 30

Step-by-step explanation:

The demand for a good is the quantity of that good that the demanders are willing to purchase at a given price.

Then, the Demand Curve relates the quantity that a consumer would be willing to buy as a function of price.

You seek to determine the linear equation that relates the price to the demand Q = m * P + b where Q is the quantity demanded at a price P, and compared with the equation of the straight line y = mx + b, m is the slope and b is the ordinate to the origin.

On a line of the form y = m * x + b, the value of m, having two points, is calculated by:

And the ordinate to the origin b is calculated, taking the value of m, replacing any of the two points (replacing any of the two because it must give the same value of b) in the expression y = m * x + b and solving its value.

In the case of Q=m*P+b, the value of m, having two points, is calculated by:

Being:

and replacing:

you get:

m= -0.5

So, being Q=-0.5*P+b,  b is calculated by:

5= -0.5*50 + b → 5= -25 + b → 5+25= b → b= 30

10= -0.5*40 + b → 10= -20 + b → 10+20= b → b= 30

Then, the linear equation relating price to demand is Q=-0.5*P + 30

since proposition states that a number is greater than 25, if is true then the number must actually be greater than 25.

this implies that all possible options, except 24, can be accepted