Equations are solved on the basis of a certain system, on the same basis. Find…
2022
Equations are solved on the basis of a certain system, on the same basis. Find out the correct answer for the equation, if 5 × 8 = 28, 3 × 7 = 12, 8 × 6 = 35, then 13 × 13 is equal to –
- A.
169
- B.
148
- C.
144
- D.
130
Attempted by 73 students.
Show answer & explanation
Correct answer: C
Rule used: result = a × b − (a + b − 1).
Check the given examples:
5 × 8 = 40 − (5 + 8 − 1) = 40 − 12 = 28
3 × 7 = 21 − (3 + 7 − 1) = 21 − 9 = 12
8 × 6 = 48 − (8 + 6 − 1) = 48 − 13 = 35
Apply the rule to 13 × 13:
13 × 13 = 169 − (13 + 13 − 1) = 169 − 25 = 144