Answer:
Budget Line is the graphical representation of goods combinations, which a consumer can buy - given prices & income (spending all income)
Equation : X.Px + Y.Py = M
{where X & Y are quantities of goods X & Y ; Px & Py are prices of goods X & Y}
a. Putting price of : X= medical services ; Y = other goods ; M = 100 :-
Budget Line : 4X + 5Y = 100
Budget Set represents good combinations, which a consumer can get - given prices & income (not necessarily spending all income)
Equation : X.Px + Y.Py ≤ M. All the area below Budget Line is Budget Set.
b. Market rate of substitution is the slope of budget line which is equal to price ratio of the goods i.e Px/Py = 4/5 = 0.8
c. Increase in Px: reduces the intercept of the axis representing Good X consumption & rotates the curve inwards on that axis. As - less of that good can be consumed with same income, due to price rise.
d. Slope of Budget Constraint: is price ratio of the two goods (Px/Py), as it denotes the amount of a good needed to be sacrifised for gaining an additional unit of the other good.