An airplane descends 1.6 miles to an elevation of 6.95 miles. Find the elevation of the plane before its descent.
The initial elevation of the plane was
Smiles.

Step-by-step explanation:    First, let's call the starting elevation of the plane: e

We can then write an equation representing this problem as:    

e−1.5mi=5.25mi

Now, add 1.5mi  to each side of the equation to solve for e

while keeping the equation balanced:

e−1.5mi + 1.5mi=5.25mi + 1.5mi

e−0=6.75mi

e=6.75mi

The plane's starting elevation was 6.75 miles

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40