Задача по уголовному праву

Problem 5. Ivanov was seriously ill daughter, who was in a nursing home. Mother had to quickly go for it. Since this trip was a large expense, but money from her at that time was not, Ivanov turned to a neighbor asking Gureeva lend her the necessary sum. Gureeva refused to give money, but Ivanova offered to sell her diamond ring, which has long wanted to buy. The ring was valued at a thrift store in 10000 rubles. Using the difficult circumstances in which there was Ivanov Gureeva said it would buy the ring only 250 rubles. The situation was hopeless Ivanova: time to look for another buyer did not have to borrow money there was nobody. Ivanov was forced to agree to the proposed terms.
A few months later, when her daughter recovered, Ivanov asked the legal advice with a request to give advice: if she can demand the cancellation of the sales contract and the return of her ring, sold much cheaper than it really worth it?

solution to the problem is painted on a sheet 3