What's going on here? Up until now we've had only one consonant "in the basement." All of a sudden we've shoehorned two consonants ( ) into the bottom of the syllable.
This is called a consonant cluster. Here's the general rule: if the syllable following a cluster starts with a vowel sound, the second consonant attaches itself to the vowel; that means you pronounce:
If there's a consonant starting the syllable after the cluster, well, there's a whole bunch of rules that tell you what to do. The usual result is that only one of the two consonants is pronounced; the other one vanishes.
My advice for now: recognize that consonant clusters exist, and consult a good book or a good teacher if you need to know the pronunication rules.