formula for calculating the value of year(2016) production in year(2015) prices, given quantities and prices of 2 goods for both 2015 and 2016 years?...

What is the formula for calculating the value of year(2016) production in year(2015) prices, given quantities and prices of 2 goods for both 2015 and 2016 years?

For example product A in 2015 (Q=100, P=20) in 2016 (Q=110, P=25). Product B in 2015 (Q=25, P=25) in 2016 (Q=30, P=30)