Answer:
Independent Variable, Domain = Charity amount
Dependent Variable, Range = Donation amount
Explanation:
Independent Variable is the causal variable. Dependent variable is the resultant or effected variable.
In this case, organisation donates money, a constant value (250) & a proportion (half) of charity. So, independent variable (causal) is charity, effecting the dependent variable ie donation.
Equation : Let donation = d, charity = c. Given : d = f (c) , where d = 250 + c/2
Domain is set of of all values for which a function is defined, range is the set of all values that f takes. So, domain is independent variable - charity & range is dependent variable - donation.