You can put this solution on YOUR website! It's best to work in decimal than fractions whenever possible.
(-.8+.7)/.75=-.1/.75=-.1333333 answer.
If you must work in franctions then:
[(-4/5+7/10)]/3/4
[(-4*2+7)/10]/3/4
[(-8+7)/10]4/3
-1/10*4/3
-4/30 or -.133333 answer.