Answer:
If he got them all today the next closest would be 40 days from now. 5*8=40 so 40 is the next closest these two would arrive at the same time, from here we know that 4 and 10 are factors of 40 so he will also get model railroads on this day.
Step-by-step explanation:
18
Half of 36 is 18.
Radius is half of diameter
<40, 28, 72>
y and z are the following vectors:
y = <2, 6, 8>
z = <7, -2, 6>
To find 6y + 4z, first compute the scalar multiplications:
6y = <6*2, 6*6, 6*8> = <12, 36, 48>
4z = <4*7, 4*-2, 4*6> = <28, -8, 24>
Then, add the obtained vectors, as follows:
6y + 4z = <12 + 28, 36 - 8, 48 + 24> = <40, 28, 72>