Need help with number 8

x = 14 2/3

Step-by-step explanation:

it is a parallelogram.

that means AB is parallel to CD, and AD to BC.

it also means that the total angles at B and D must be equal. and the total angles at A and C.

and the sum of all angles in a parallelogram is 360 degrees.

so, we have

360 = 2×(4x + 4x + 8) + 2×(x + 10 + 2x + 8) =

= 8x + 7x + 16 + 2x + 20 + 4x + 16 =

= 21x + 52

308 = 21x

x = 14.666666666 = 14 2/3

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