The expression given is:

And we need to find the value of x.
To solve for x, we need to have the variable x alone on one side of the equation, for this, we multiply both sides of the equation by 3:

Solving the left-hand side we have to multiply 3 times 7 and divide that by 5. Since 3*7 is equal to 21:

Continuing with the left-hand side, the division of 21/5 is equal to 4.2:

Finally, solving the right-hand side, we note that 3/3 is 1, thus, we will only be left with x:

The value of x is 4.2.
Answer:
x = 4.2