SOLUTION: A first number plus twice a second number is 11. Twice the first number plus the second totals 31. Find the numbers.

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Question 1141757: A first number plus twice a second number is 11. Twice the first number plus
the second totals 31. Find the numbers.
Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20060)   (Show Source):
You can put this solution on YOUR website!
A first number [x] plus [+] twice a second number [2y] is [=] 11.

x + 2y = 11

Twice the first number [2x] plus [+] the second [y] totals [=] 31.

2x + y = 31 So the system of two equations with 2 unknowns is
Find the numbers.
Solve that system by substitution or elimination. If you have trouble, ask me for help in the space below and I'll get back to you be email. Edwin

Answer by ikleyn(52813)   (Show Source):
You can put this solution on YOUR website!
.

            On the way, Edwin made an error in treating his system of equations.
            So I came to bring the correct solution.

From the condition, you have these two equations in two unknowns x + 2y = 11 (1) 2x + y = 31 (2) From equation (1), express x = 11 - 2y and substitute it into the second equation. You will get 2*(11-2y) + y = 31. Simplify and solve for y 22 - 4y + y = 31 -3y = 31 - 22 -3y = 9 y = = -3. Then x = 11 - 2y = 11 - 2*(-3) = 11 + 6 = 17 ANSWER. x = 17, y = -3.