Justify each step in solving the equation 4x = 7 (x-3) by writing a reason for each statement.

The steps of solving the given equations are,

              Statement                              Reason

1.    4x = 7 (x-3)                                   Given

2.    4x = 7x - 21                                  Distributive property

3.    -3x = -21                                       Subtraction property of equality

4.      x = 7                                           Division property of equality

Note :

By Distributive property, a value can distributive inside the bracket,

I.e. a ( b + c ) = ab + ac

By  Subtraction property of equality, we can subtract a number both sides of an equation,

a = b ⇒ a - c = b - c

By Division  property of equality we can divide both sides of an equation by a same number,

I.e.

a = b ⇒ a/c = b/c

Where, a, b and c are real numbers.                  

its 50 miles away from the starting point