Question 72 (d)
Find the value of (20+30+40)(40−30−20)
(20+30+40)(40−30−20)=(1+1+1)(1−1−1)=(3)(−1)=−3
Question 72 (e)
Find the value of 2×3×4÷20×30×40
Question 72 (f)
Find the value of (80−20)×(80+20)