Question

If10,20 x and 40 in a proportion the value of x will be

Answer 1

a:b::b:c
a=10
b=20x
c=40
10/20x=20x/40
400x^2=400
X^2=1
X=1

Answer 2

10 × 40 = 20 × x
400 = 20x
x =400/20
x = 20ans