Twice a certain number is subtracted from 9 times the number. The result is 21. Find the number.​

3

Step-by-step explanation:

Let x represent the number.

Create an equation to represent the situation, and solve for x:

9x - 2x = 21

7x = 21

x = 3

So, the number is 3.

on friday there were 15 birds

the total estimated nappy use.=10,500,000

step-by-step explanation:

given that on an average the average baby uses 3528 napkins.

in a particular year 2014, the number of births were 299697 in new south wales.

rounding off the number of births to the nearest hundred thousand we have

no of birtsh = 300000

also rounding off the average usage to nearst thousand we get

average use of a baby = 3500

hence total number of nappy estimated to be used = 3500x300000

= 10,500,000

answer is 10,500,000 nappies