Two figures are similar if their angle measures are the same and corresponding sides are proportional.
The bottom left figure has angle measures of 37°, 53° and 90°. The bottom right figure has the same angle measures.
The sides of the bottom left figure have lengths of 3, 4 and 5. The corresponding sides of the bottom right figure have lengths of 6, 8 and 10. This means they are proportional.
If the problem is 3(15x - 17), none of those expressions are correct. You would multiple the 3 to each term (hence the "distributive" part) to get 45x - 51.
<span>I rounded up the whole number as if each student sells only 3 sweatshirts, it is too little to pay for the whole trip, therefore the number must be 4. Hope that helps!</span>