Angles in a triangle always add to 180 degrees. 180=(8x+3degrees)+(10x-4 degrees)+91
180-91=89 89=(8x+3 degrees)+(10x-4 degrees) 89-3= 86 86+4=90
(8x+10x=18x) 18x=90
divide bothe sides by 18
x = 5
-8 x -2/3 =5.3333 so five point three repeating
Answer: 96 ways
In this case, the freshman must take one class each from Science(6 courses), Humanities(4 courses) and Mathematics( 4 courses).
Then to know how many ways she can arrange you just need to multiply the each course count (it would different if she has to take more than one class).
The calculation would be: 6 x 4 x 4= 96 ways.
The teacher probably wants you to multiply cause area refers to that