Answer: They earned $720 from the T-shirts.
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 :-
![5x+2.50y=840\\x=3y](https://img.qammunity.org/2020/formulas/mathematics/high-school/ytx773wvowu7oltt0h58tbl41lug9zofs8.png)
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 =
![144*5=\$720](https://img.qammunity.org/2020/formulas/mathematics/high-school/u1yv444ej0wpdu1l9dkqntqwnt4s4r5grt.png)
Hence, they earn $720 from the T-shirts.