SOLUTION: the sum of two numbers is 21. the smaller number is three more than half the larger number. find the solution by writing and solving a system of equations algebraically.

Algebra ->  Customizable Word Problem Solvers  -> Numbers -> SOLUTION: the sum of two numbers is 21. the smaller number is three more than half the larger number. find the solution by writing and solving a system of equations algebraically.      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 967876: the sum of two numbers is 21. the smaller number is three more than half the larger number. find the solution by writing and solving a system of equations algebraically.
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
x and y are the two numbers.
.
x%2By=21
x=21-y Use this to substitute for x below.
x=%281%2F2%29y%2B3 Substitute for x from above.
21-y=%281%2F2%29y%2B3 Add y to each side.
21=1.5y%2B3 Subtract 3 from each side.
18=1.5y Divide each side by 1.5.
12=y ANSWER 1: The larger number is 12.
x=21-y=21-12=9 ANSWER 2: The smaller number is 9.