SOLUTION: Write a system of two equations in two variables to solve the problem. On a mother's 21-mile commute to work, she drops her daughter off at a child care center. The first part

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Write a system of two equations in two variables to solve the problem. On a mother's 21-mile commute to work, she drops her daughter off at a child care center. The first part       Log On


   

Question 788226: Write a system of two equations in two variables to solve the problem.
On a mother's 21-mile commute to work, she drops her daughter off at a child care center. The first part of the trip is 9 miles less than the second part. How long is each part of her morning commute?
first part mi
second part mi

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
f for part one, as in First;
s for part two, as in Second.

f%2Bs=21 because the two parts together are the 21 mile trip.

f=s-9, according to the description's latter part.

The rest of the solution is for you to handle. The more difficult work is to analyze and obtain those two equations. (A simple substitution should be obvious).