What percentage of the blocks is shaded in the picture?

First, find the number of shaded blocks.
shaded blocks = 8 × 3
shaded blocks = 24
There are 24 shaded blocks

Second, find the number of the blocks
all blocks = 8 × 10
all blocks = 80
There are 80 blocks in total.

Third, write a fraction defining the shaded blocks compare to the blocks in total
fraction = 24/80
simplify
fraction = 3/10

Fourth, change the fraction into percent
Percent means per hundred. Change the denominator to 100
fraction = 3/10
percent = (3 × 10) / (10 × 10)
percent = 30/100
percent = 30%

The percentage of the blocks shaded in the picture is 30%