CDF in Probability

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$$f(x)=\left\{\begin{array}{ll} C & \text { for }-3 \leq x<3 \\ Dx & \text { for } 3 \leq x<5 \\ 0 & \text { otherwise } \end{array}\right.$$

Given that $P(-3 \leq x < 3) = \frac{2}{3}P(3 \leq x < 5)$, What is the cumulative distribution function $CDF(x)$.

So far I have tried to solve the following:

$P(-3 \leq x < 3) = \frac{2}{3}P(3 \leq x < 5)$

$\int_{-3}^x f(x)dx$ = $\frac{2}{3} \int_{3}^x f(x)dx$

$\int_{-3}^x (C)dx$ = $\frac{2}{3} \int_{3}^x (Dx)dx$

$\int_{-3}^x (C)dx$ = $ \frac{2}{3} \int_{3}^x (Dx)dx$

$ \left[Ax\right]_-3^x $ = $\frac{2}{2*3} \left[D* x^{2}\right]_3^x $

C [3 - (x)] = $ \frac{1}{3} \left [D * (x^{2} - 3^{2}\right] $

(3-x)* C = $ \frac{D*(x^{2} - 3^{2})}{3} $

C = $ -\frac{D*(x + 3)}{3} $

How do I find the values for C and D and then calculate the CDF?

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$\int_{-3}^{x}f(t)dt \neq \frac{2}{3} \int_{3}^{x}f(t)dt $, this need not be true

but

$\int_{-3}^{3}f(x)dx = \frac{2}{3} \int_{3}^{5}f(x)dx $

other equation will be

$\int_{-\infty }^{\infty }f(x)dx = 1 $

Get $C,D$ from above two equations

Finally CDF = $\int_{-\infty }^{x }f(t)dt$