what is -14/8 + 25%

Really your question does not make much sense.

You want to add 25% of what ?

14/8 = 1.75

to add 25% to your answer you multiply your answer by 1.25

1.75 * 1.25 = 2.1875

Remember the minus sign.

-14/8=-1.75

-1.75*1.25=-2.1875