Guys help i have an F but this assignment will get me back to an A

What is the value of x in the this question ?

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 . reset next

Dots sells a total of 279 t-shirts ($2) and shorts ($4). in april total sales were $670. how many t-shirts and shorts did dots sell?