Teacher: In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
Teacher: Now, understand the problem? If you are still confused, see the following example:
In early work , Rutherford discovered the concept of radioactive half-life, the radioactive element radon, and classified three types of radiations: alpha, beta and gamma radiation .

Solution: Rutherford discovered the radioactive half-life, the chemical element radon, and the three parts of radiation which he named Alpha, Beta, and Gamma .

Reason: The output sentence is a simplified version of the input sentence.

Now, solve this instance: After the arrival of the first production 707 in 1957 the Dash 80 was adapted into a general experimental aircraft and used by Boeing to test a variety of new technologies and systems .
Student:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
After the first 707 was made in 1957 , the Dash 80 was changed into a test planes for other things .