How do you know if a number is directly proportional to another number?
in this question x is directly proportional to y
x=60
y=35
how is x directly proportional to y

x ∝ y

x = 12/7y

Step-by-step explanation:

Direct Proportion = x ∝ y

x = ky where k is the constant.

Substitute the values in:

60 = 35k

Now solve for k.

60/35 = k

k = 12/7

x = 12/7y

As the value of x increases the value of y increases proportionally.

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

tube or goog would be a great resource to with that question