Verified answer

Statement:

The sum of two numbers is 90, their difference is 40. Find the numbers.

Representation:

• Let c and d be the two numbers.

Equation:

• c + d = 90
• c - d = 40

• c + d = 90
• c - d = 40

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• c = 40 + d
• 40 + d + d = 90
• 40 + 2d = 90
• 2d = 90 - 40
• 2d = 50
• 2[2d = 50]2
• d = 25

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• c + d = 90
• c + 25 = 90
• c = 90 - 25
• c = 65

• c = 65, d = 25