Suspension of a CW complex

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I want to prove that the suspension $\Sigma X$ of a CW-complex $X$ is a CW-complex, buy I'm starting with CW-complexes and I don't have a clue of how start, so I'd appreciate any help. Thanks.

$$\Sigma X=\frac{X \times I}{X \times \{0,1\}}$$

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It is a general result (that I invite you to prove) that the product of CW-complexes (one of which is finite) is still a CW-complex, using the product of the cells involved. Hence $X \times I$ is a CW-complex. Moreover, $X \times \{0,1\}$ is a subcomplex thereof, so that $(X \times I,X \times \{0,1\})$ is a relative subcomplex (see this http://www.math.uchicago.edu/~may/CONCISE/ConciseRevised.pdf , at page 73-74): this implies that $\Sigma X=(X\times I) /(X \times \{0,1\})$ is a CW-complex.