What is the value of f(x)=-7 and f(x)=63

56

Step-by-step explanation:

Given expression:

          x - f(x) = -7

            f(x) = 63

Unknown:

The value of x  = ?

Solution:

We can easily solve this problem by simple substitution:

         Since;

             x - f(x) = -7

  and f(x) = 63;

           x - 63  = -7

            x  = -7 + 63

             x  = 56

you never say the total so we cant find the percentage used for petrol

step-by-step explanation:

i you goofed up when writing this, because hnot is not a word minusf is not either. i cannot answer   because of that.

step-by-step explanation: