I am not sure about how to approach this problem, because I don't understand transformations of random vectors. Help?

Problem 5. Suppose that that X1 ~ N(0,1) and X2 ~ N(0,1) are inde pendent random variables. Use your knowledge on transformations of random vectors to nd the joint probability density function of Y1 = 01X1 + 51 Y2 = 0,ng + 52 where (12- 75 0 and bi- ER for 2' = 1,2