Sum product by row across two dataframes/matrix in r -

i have 2 data frames, each 2 columns. matrices same dimensions if helps in calculations.

what want sum product of these data frames of respective positions/rows.

for example solution following in 1 column.

 21 = 1*1+10*2  42 = 2*1 +20*2 63 = 3*1 + 20*2   a=data.frame(c_1=c(1,2,3),c_2=c(10,20,30))   b=data.frame(c2_1=c(1,1,1),c2_2=c(2,2,2)) 

you can try

rowsums(a*b) [1] 21 42 63