NCERT Exemplar Solutions
Class 7 - Mathematics - Unit 1: Number System - Problems and Solutions
Question 124

Question. 124

124. Evaluate using the distributive property:

(i) \(−39\times99\)

(ii) \((−85)\times43 + 43\times(−15)\)

(iii) \(53\times(−9) − (−109)\times53\)

(iv) \(68\times(−17) + (−68)\times3\)

Answer:

(i) −3861

(ii) −4300

(iii) 5300

(iv) −1360

Detailed Answer with Explanation:

(i) \(−39(100−1)=−3900+39=−3861\).

(ii) Factor 43: \(43[(−85)−15]=43(−100)=−4300\).

(iii) Factor 53: \(53[(−9)+109]=53\times100=5300\).

(iv) Factor 68: \(68[(−17)−3]=68(−20)=−1360\).

NCERT Exemplar Solutions Class 7 – Mathematics – Unit 1: Number System – Problems and Solutions | Detailed Answers