Question

The ratio of books to magazines at jess house is 5:3 they are 21 magazines at jess house how many books are there?

Answer 1

First, 5/3 = 1.6
21 x 1.6 = 34.99999999
But, when I put it in a calculator, the 1.6 was repeated so:
Round 34.99999999 to 35
35 books

Answer 2

It's the same as writing them as fractions
$\frac{5}{3} = \frac{x}{21}$
x= books

Cross multiply.
5×21
And
3×x

$105 = 3x$
divide 3 on both sides

x=35