The ratio of money in Terry's bank account to Faye's bank account was 3:7. Terry then put £220 in his account and Faye withdrew £300 from her account.
They now had the same amount in their accounts.
How much did Terry initially have?

£390

Step-by-step explanation:

 The ratio of money in bank:

        Terry  :    Faye

             3      :     7

Terry put £220 in his account

Faye withdrew £300 from her account

 Unknown:

Initial amount Terry had = ?

Solution:

 Let the real amount terry has = 3x

  Faye will have = 7x

Now;

        3x + 220  = 7x -300

 Solving this equation:

         3x + 220  = 7x -300

       3x - 7x = -300 - 220  

           -4x  = - 520

             4x = 520

               x = 130

Originally, Terry has 3x = 3 x 130 = £390

for finding the midpoint of any given 2 pair of points simply add the respective x coordinates with other x coordinate and the y coordinate with other y coordinate and divide them by 2

in your question it will be :

(3+1)/2 for the x coordinate of mid point i.e 2

[8+(-4)]/2 for the y coordinate of midpoint i.e 2

so coordinates of mid point of points (3,8) and (1,-4) will be (2,2)