The answer to your question is C
9x-20=7
9x=27
x=3
Hope that helps you :)
A right angle triangle normally relates to Pythagoras Theorem , and this is related to the hypotenuse, the answer maybe the hypotenuse. As the other sides are the opposite and alternative
(1.75 + 2 x 0.25 + 5 x 0.05) x 24= 17