-10y^2 + (-3y^2) - 4y^2 - (-6y^2) =
-10y^2 - 3y^2 - 4y^2 + 6y^2 =
-17y^2 + 6y^2 =
- 11y^2
His balance will be $6 because -19 - 35 = -54, he added 60 to the -54 so that makes 6 or $6
Use elimination
-x - y = -9
x - y = 3
Add both equations
-2y = -6, y = 3
-x -(3) = -9
-x = -6, x = 6
Final answer: x = 6, y = 3
Let's analyse the function

The amplitude is A, so we want A=1.5
Now, we start at x=0, and we have 
After one second, i.e. x=1, we want this sine function to make 330 cycles, i.e. the argument must be 
So, we have

so, the function is

0.26 * 1/10 = 0.026
because 1/10 = 0.1
0.26 * 0.1 = 0.026