The answer is C because he starts off with 16 dollars and then spends it all on 4 rides
Y =x+4/9
9 (y=x+4/9)
9y=9x+4
9y-9y=9x-9y+4
0=9x-9y+4
0-4=9x-9y+4-4
-4=9x-9y
Standard form: 9x-9y=-4
To Prove :
Side lengths 6, 8 and 10 will make a right triangle.
Solution :
We know, by Pythagoras theorem :

Here, c is the biggest side and a and b are other sides.
Putting given values in above equation.

Since, LHS = RHS .
Therefore, lengths 6, 8 and 10 will make a right triangle.