The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales? they earned $128 from the t-shirts. they earned $144 from the t-shirts. they earned $360 from the t-shirts. they earned $720 from the t-shirts.

They earned $720 from the T-shirts.

Step-by-step explanation:

Given : The number of T-shirts sold was 3 times the number of hats.

The profit was $5 for each T-shirt sold and $2.50 for each hat sold.

The students raised $840 for the charity.

Let x denotes the number of T-shirts sold and y denotes the number of hats sold.

then, we will have the given system :-

It is also given that they used the system below to analyze their success and found the solution to be (144, 48).

It means x= 144

It means the number of t-shirt sold = 144

The amount they earn from t-shirt =

Hence, they earn $720 from the T-shirts.

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this