X + y = 15
Rearrange this to isolate for x.
x = 15 - y
x + z = 20
Rearrange this to isolate for x also.
x = 20 - z
Since they are both equal to x, that means they are equal to each other (x = x)
Set them equal to each other.
15 - y = 20 - z
Now, isolate for y.
y = 15 - 20 + z
Now, use y + z = 25 and isolate for y.
y = 25 - z
Since they are both equal to y, we set them equal to each other.
15 - 20 + z = 25 - z
Solve for z
z + z = 25 - 15 + 20
2z = 30
2z/2 = 30/z
z = 15
Now you can plug the value for z into the other equations to find y and x.
x + z = 20
x +15 = 20
x = 20-15
x = 5
y + z = 25
y + 15 = 25
y = 25 - 15
y = 10
The longest piece is 24 ft and the smallest piece is 4 ft
Average speed = 
Ishan's Speed uphill = 10mph
Time taken = 18 minutes = 18/60 = 3/10 hours
Now distance = rate × time
Distance traveled by Ishaan up hill = 10 × 3/10 = 3 miles
Now returning back home
Distance = 3 miles
Rate = 30 mph
So time taken = distance/ rate = 3/30= 1/10 hours = 1/10 ×60 = 6 minutes.
Now total distance traveled = 3 + 3 = 6 miles
Total time taken = 18 + 6 = 24 minutes = 24/60 = 2/5 hours
Average speed
= 
= 15 mph
Ishaan's average speed for the entire trip from home to the gift store and back is 15mph
X=B^1 + b^7 . i found my answer by you need to find the slope of the numbers between the table.
The first fish has an integer of -4 and the other fish has an integer of -3.
-3 is greater because -4 is one less of -3. If you put it on a line then -3 is closer to the 0 then -4.