\\(\\begin{array}{l}{\ ext { (i) } P_{1}=\\operatorname{Rs} 4} \\\\ {P_{2}=R s 5} \\\\ {M=R s 20} \\\\ {\ ext { Equation of the budget line }=P_{1} x_{1}+P_{2} x_{2}=M} \\\\ {4 x_{1}+5 x_{2}=20}\\end{array}\\)
(ii) If Rs 20 is entirely spent on good 1, then the amount of good 2 demanded will be zero i.e., x2 = 0 as the consumer has no income left to spend on good 2.
\\(\\begin{array}{l}{4 \\mathrm{x}_{1}+5(0)=20} \\\\ {4 \\mathrm{x}_{1}=20} \\\\ {x_{1}=\\frac{20}{4}} \\\\ {x_{1}=5} \\\\ {\ ext { Amount of good 1 consumed }=5 \ ext { units }}\\end{array}\\)
(iii) If Rs 20 is entirely spent on good 2, then x1 = 0, as the consumer has no income left to spend on good 1.
\\(\\begin{array}{l}{4(0)+5\\left(x_{2}\\right)=20} \\\\ {5\\left(x_{2}\\right)=20} \\\\ {x_{2}=\\frac{20}{5}} \\\\ {x_{2}=4 \ ext { units }} \\\\ {\ ext { Amount of good } 2 \ ext { consumed }=4 \ ext { units }}\\end{array}\\)
(iv) Slope of the budget line =
\\(\\frac{-P_{1}}{P_{2}}\\)
\\(=\\frac{-\ ext { Price of good } 1}{\ ext { Price of good } 2}=-\\frac{4}{5}=-0.8\\)