Hello
x
x +5
x + 7
x + x + 5 + x + 7 = 21
3 x = 21 - 12
3 x = 9
x = 3
3 , 5 et 7 pouces
Now, let's do the same as we did for the previous one here.

notice again, how did we get 84 for the 4th element's coefficient? well 36 * 7 / 3. and so on. And you can just expand it from there.
Answer:
Step-by-step explanation:
1
the initial level is below normal so it is represented by a negative number. the level continued to decrease in June and July so those changes are also represented by negative numbers. find the sum of these values to find what the new level was with respect to the normal level
2
write the mixed numbers as improper fractions
3
get common denominator
4
add the numerators since all the numbers are negative and have a common denominator. write the improper fraction as a mixed number