211k views
5 votes
A first number plus twice a second number is 5. Twice the first number plus the second totals 13. Find the numbers.

User Nkalvi
by
8.0k points

1 Answer

0 votes

Let a and b = the numbers we must find.

a + 2b = 5.....Equation A

2a + b = 13.......Equation B

We have a system of equations in two variables.

I will solve A for little a.

a + 2b = 5

a = 5 - 2b

Now I will plug 5 - 2b for a in B.

2(5 - 2b) + b = 13

10 - 4b + b = 13

-3b = 3

b = -1

To find a, replace b with -1 in EITHER A or B.

I will use Equation A.

a + 2b = 5

a + 2(-1) = 5

a - 2 = 5

a = 7

The two numbers are -1 and 7.

Understand?

User IraSenthil
by
8.6k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories