Solve this multiple-choice question and choose the correct option.

Problem Restatement Use the difference-of-squares identity to evaluate 642 − 362 and solve for x in 20x. Concept / Approach (A2 − B2) = (A − B)(A + B). Step-by-Step Calculation 642 − 362 = (64 − 36)(64 + 36) = 28 × 100 = 28002800 = 20x → x = 2800 ÷ 20 = 140 Final Answer 140

Curioustab

If 64<sup>2</sup> − 36<sup>2</sup> = 20 × x, find the value of x.

Aptitude Numbers Difficulty: Easy

Choose an option

A

120
B

140
C

160
D

180
E

None of these

Answer

Correct Answer: 140

Explanation

Problem Restatement

Use the difference-of-squares identity to evaluate 64² − 36² and solve for x in 20x.

Concept / Approach

(A² − B²) = (A − B)(A + B).

Step-by-Step Calculation

64² − 36² = (64 − 36)(64 + 36) = 28 × 100 = 28002800 = 20x → x = 2800 ÷ 20 = 140