Duration of a portfolio

If a portfolio have 40% UK stock and 60% euro stock , the duration of uk stock is 7 and the duration of euro stock is 5, the correlation between uk and euro stock is 0.55 , find the portfolio value impact on 100 b.p interest rate change ?

Duration of stock?

Maybe you refer to betas @ jesswong. If you do so, interesting question. What ist the beta then?