Question

Three times a number increased by two

times another number equals 28. Two
times the first number increased by
three times the second number equals
27. Find the two numbers.

Answer 1

5 and 6

Explanation:

let the 2 numbers be x and y , then

3x + 2y = 28 → (1)

2x + 3y = 27 → (2)

multiplying (1) by 2 and (2) by - 3 and adding will eliminate x

6x + 4y = 56 → (3)

- 6x - 9y = - 81 → (4)

add (3) and (4) term by term to eliminate x

0 - 5y = - 25

- 5y = - 25 ( divide both sides by - 5 )

y = 5

substitute y = 5 into either of the 2 equations and solve for x

substituting into (1)

3x + 2(5) = 28

3x + 10 = 28 ( subtract 10 from both sides )

3x = 18 ( divide both sides by 3 )

x = 6

The 2 numbers are 6 and 5

Answer 2

r={21}

Step by Step Explanation:

PREMISES

Two times three plus a number, say, r=27

ASSUMPTIONS

Let r=the number

CALCULATIONS

The numerical expression “two times three plus a number r=27” can be denoted as:

(2×3)+r=27

6+r=27

6–6+r=27–6

0+r=27–6

r=21

PROOF

If r=21, then the equations

(2×3)+r=27

6+21=27 and

27=27 prove the root (zero) r=21 of the statement (2×3)+r=27

PREMISES

Two times three plus a number, say, r=27

ASSUMPTIONS

Let r=the number

CALCULATIONS

The numerical expression “two times three plus a number r=27” can be denoted as:

(2×3)+r=27

6+r=27

6–6+r=27–6

0+r=27–6

r=21

PROOF

If r=21, then the equations

(2×3)+r=27

6+21=27 and

27=27 prove the root (zero) r=21 of the statement (2×3)+r=27