18 is 60% of 30. I know this because 10% of 30 is 3 and 3 * 6 is 18
So based on place values, the One's place is occupied by 4. To round to this digit, you go one number to the right. If that number is 5 or higher, you add one to 4. If it is less than 5, you don't add any to 4. Since 7 is greater than 5, you add 1 to 4, giving you 5, since you can now remove all the other numbers to the right.
5.
It's a similar triangle so the ratios of corresponding sides should be equal which means
BC/EF = AB/DE
21/14 = AB/10
AB = 21/14 * 10 = 15 cm
X=10 that how u would get the 12 and the 2
