I'm having trouble with Khan Academy and this question is hard. -5/8 +(-8/5)

please help

Rules for these questions

- and - is equal to +

+ and - is equal to -

According to these rules, we have a + and - so we change it to a -

The new equation is

-5/8-8/5

Which is equal to

-25/40-64/40=89/40.

You may simplify it

I hope this helps, if it's wrong blame me..

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m

true

explanation: