What is -5 + 15

-10
10
20
-20

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

The functions below show the amount of money bella and sweet t had saved after earning money for doing chores. which description best compares the two functions?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?