Learn German: Die Autos und die Häuser kosten viel Geld. - The cars and the houses cost a lot of money.

No, in the singular they are both neuter (das Auto and das Haus). However, in German, the definite article for all plural nouns is always die, regardless of the noun's original gender.

Why does Autos end in an -s for the plural? I thought German plurals usually end in -e or -en.

While those endings are very common, German uses an -s ending for nouns borrowed from other languages, or words that end in vowels like -a, -i, -o, or -u. Because Auto ends in an -o, it becomes die Autos.

How do we form the plural Häuser from Haus?

Some German nouns form their plural by adding an -er to the end. When this happens, the main vowel inside the word usually gets an umlaut if it is an a, o, or u. So the a in Haus changes to ä, giving us die Häuser.

Why is the verb kosten here instead of kostet?

The verb must match the subject of the sentence. Since the subject is plural (the cars and the houses), we treat it as the plural 'they'. The 'they' form of verbs ends in -en, so we use kosten.