542 x 79 = 475 x 81 = 490 ÷ 33 =

$$542 \times 79$$

First, multiply 542 by 9:

$$542 \times 9 = 4878$$

Next, multiply 542 by 70:

$$542 \times 70 = 37940$$

Now, add the two results:

$$4878 + 37940 = 42818$$

The result is $\boxed{\text{42818}}$.

$$475 \times 84$$

First, multiply 475 by 4:

$$475 \times 4 = 1900$$

Next, multiply 475 by 80:

$$475 \times 80 = 38000$$

Now, add the two results:

$$1900 + 38000 = 39900$$

The result is $\boxed{\text{39900}}$.

$$990 \div 33$$

Divide 990 by 33:

$$990 \div 33 = 30$$

The result is $\boxed{\text{30}}$.