4. Kalum used a $20 bill to pay for items totaling x
dollars. He received $16.21
in change. Write and solve
an ADDITION equation to
determine how much Kalum
spent on his items.

I don’t know how to use addition on THIS problem!

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