The number is (2√3) / 3
To find the missing number, convert what it says in words to an equation:
[tex]15 {x}^{2} = 20x[/tex]
Divide both sides by 15:
[tex] {x}^{2} = \frac{20}{15} \\ \\ {x}^{2} = \frac{4}{3} [/tex]
Take the square root:
[tex]x = \sqrt{ \frac{4}{3} } \\ \\ x = \frac{2}{ \sqrt{3} } \\ \\ x = \frac{2 \sqrt{3} }{3} [/tex]
