Question

When a number x is multiplied by 4 the result is 2/5 what is the vaule of x

Answer 1

2/5 as a decimal is 0.4 
4*0.1=0.4 
meaning x is 0.1

Answer 2

4x=2/5
x=(2/5)/4
x=(2/5)/(4/1)
x=2/5*1/4
x=2/20
x=1/10
x=0.1

Hope this helps :)