a minus 5 over 8 equal negative 1 over 4

if you mean a-5/8 = -1/4 then

a-5/8 = -1/4

=> a = 5/8  - 1/4

=> a = 5/8 - 2/8

=> a = 3/8

and if you meant (a-5)/8 = -1/4 then

(a-5)/8 = -1/4

=> a-5 = (-1/4) * 8

=> a-5 = -2

=> a = -2 + 5

=> a = 3

Nice setting out Novice!