Answer:
70 cars
Step-by-step explanation:
Let x cars are parked in the parking lot.
[tex]30\% \: of \: x = 21 \\ \\ \frac{30}{100} \times x = 21 \\ \\ x = 21 \times \frac{100}{30} \\ \\ x = \frac{2100}{30} \\ \\ x = 70 \: [/tex]
70 cars are parked in the parking lot.