Lois wants to average 83% on her 5 tests to assure herself a B. If she scores 72%, 90%, 85% and 88% on her first four tests, what does she need to earn on her last test to meet her goal?

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis. 3- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in part b?

How can you construct perpendicular lines and prove theorems about perpendicular lines

If the value of cos330°is√3/2 then find cos 165°.