Question

Increase a number by 21, multiply the result by 3, then subtract 9 and divide by 5. If the final result is 30, with which number did you start? What am i missing here?

Answer 1

Let x = that number.
1. x
2. x + 21
3. 3(x + 21)
4. 3(x + 21) - 9
5. (3(x + 21) - 9)/5

(3(x + 21) - 9)/5 = 30
Times 5.
3(x + 21) - 9 = 150
Add 9.
3(x + 21) = 159
Divide by 3.
x + 21 = 53
Subtract 21.
x = 32

Try the value and see if it works out.

Answer 2

Thank you for showing the steps it helped make it clear to me how to solve the problem