Answer:

Step-by-step explanation:
Given



Required
Determine the length of the base
The perimeter of an isosceles triangle is:



Collect Like Terms


Divide both sides by 7

To get the base, we substitute 19 for x in 


She subtracted on the right side, when she should've added.
The answer is B
"Helen should have added 17 to both sides of the equation."
2x + 7 = 21
first you subtract the 7 from the 7 and 21 which will leave you with 2x=14
then see what multiples with 2 to get 14 which is 7!
Approximately 1.7 miles per hour
Answer:
x=0,64
Step-by-step explanation: