Graph of Fractional Part Function

Q. The number of solutions of $2\left[x\right]=x+2\left\{x\right\}$ is/are

Q. The number of solutions of the equation $\left[3x\right]-[x+1]=3x$, where $[.]$ denotes greatest integer function, is equal to

Q. The number of solutions of the equation $\frac{x}{7}=\left\{x\right\}$ is
(where {.} is the fractional part function)

1. $0$
2. $7$
3. $1$
4. $6$

Q. The number of solutions of the equation $\frac{x}{7}=\left\{x\right\}$ is
(where {.} is the fractional part function)

1. $0$
2. $1$
3. $6$
4. $7$

Q. The number of solutions of the equation $\frac{x}{7}=\left\{x\right\}$ is
(where {.} is the fractional part function)

1. $0$
2. $1$
3. $6$
4. $7$