Which value of t makes the two matrices inverses of each other?

|-4 6| |2 3|
|3 -4| |1.5 t|

A.-3
B.-2
C.2
D.3

Can someone me with this problem i don't understand i need

Rationalize the denominator- 12x/√x-10

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)