Question

In an office building, 39 offices are currently being rented. This represents 30% of the total units. How many offices are there in the building?

There are __ offices in the building

Answer 1

ANS. = 130

30% or 30/100=39offices

use cross multiplication

100/30 x 39/1 (note 30/100 is inversed to 100/30) math. law

10/3 x 39/1 (using divisor 10)

10/1 x 13/1 (using divisor 3)

10 x 13 = 130

Ans = 130 offices

Ans.Checked

30% of 130 offices

30/100 x 130/1

3/10 x 130/1 (10 as divisor)

3/1 x 13/1 (10 as divisor)

3 x 13 = 39

39 offices

Q.E.D

Answer 2

130 offices are in the building

Explanation:

first 39/x = 30/100

secondly, you cross multiply 39 x 100 and 30 x x

100 x 39= 3900

3900/30 = 130