Which equation matches the story: Elena spends $17 and buys a $3 book and a bookmark for each of her 5 cousins. How much does each bookmark cost? 3(x+5)=17

3x+5=17

5(x+3)=17

5x+3=17

I’m really confused and need your assist me with this question i’ve never been taught

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is

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?