You need to know more information, not just the length of the hypotenuse.
If you know the length of one leg use Pythagoras theorem to find the other.
If you know the value of one other angle use trigononemtry
-3x-12> 8x + 21
+12 +12
-3x > 8x + 33
-8x -8x
-11x > 33
————-
-11
x < -3
I moved the real numbers to one side and and the variable to the other side to solve for the inequality
I also remembered somewhere that if you divide by a negative number the inequality sign switches.
A= about 75 cents -- This is because you would figure out what 5% is equal to (.05). Then, you would do .05 x 14.90 to get the amount of sales tax you will be paying. By doing this you will get .745 which is approximately .75 which would become 75 cents
b= $15.65 -- For this one, you would do the cents (.75) plus the total (14.90) So you would do 14.90+.75 which = 15.65.
Hope this helped :)