columns
A = criteria 1
B = criteria 2
C = value 1
D = value 2


how do i get the sum of all like critera 1&2 values multipled together (value 1 x value 2)

i.e.
A B C D
cat house 2 5
cat house 2 6
cat house 1 8
dog house 2 9
dog home 2 8

for cat/house as critera,...answer would be 2*5 + 2*6 + 1*8=30