Question

twice a number is equal to 40 what is the number

Answer 1

$let \: the \: number \: be \: x \\ \: then \: given \\ 2x = 40 \\ x = 20$
Hence the number is 20

Answer 2

let the number is equal to x
2x= 40
x=40/2
hence x=20
i hope it will help you