1.Let the length of the sides of the rectangular paper be 2x and 3x cm .
Given,6x² cm² =150 cm²
Therefore, the length of its sides are 2x= 2 cm*5=10 cm and 3x=3 cm*5=15 cm respectively.
2.Percentage of copper=30%
Percentage of zinc=40%
Percentage of nickel=%(100-30-40)=30%
Ratio of copper,zinc and nickel in the alloy=30%:40%:30%
Let the quantity of each metal in 20 kg alloy be 3x , 4x and 3x respectively.
By the condition,
Therefore,Amount of nickel in 20 kg alloy=3x=3*2 kg=6 kg.
3.SI on the first investment=Rs.P*R*T/100
SI on the second investment=Rs.P*R*T/100
Therefore,The first investment is better.