Question

I know the current price of goods A and B, the average income, the current demand of good A and the income elasticity, the own price elasticity and the cross-price elasticity for demand of good A.
If a reduction in prices of goods A and B and an increase in income happen simultaneously, how much will be the new demand of good A? I think that I must calculate the ΔQs as any change occurs seperately and then I sum these. Is it right?