Which one doesn’t belong

D

Step-by-step explanation:

The last one.

The other three are all in proper scientific notation.

The last one does not raise ten to scientific notation. All scientific notation is written with ten as the power after a number between 1 and 9.99999

For example 1.4 * 10^-5 or 1.7*10^16 are both correct written in scientific notation.

The last one is not 10 * 9.4^16 is not correct and is not written in scientific notation.

7 ft 6 in means 7 1/2, because 6 in is 1/2 of a foot. 7 ft 8 in means 7 2/3 because 8 in is 2/3 of a foot. 23/3 = 7 2/3. 15/2 = 7 1/2.

23/3   *   15/2   = 57 1/2

step-by-step explanation:

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads