There are two toaster, one is rated 20w,10v and second is rated 30w,15v.

They are used 2 hrs daily.

So, electric energy of first toaster in one day-

W=P.t

20w=0.020 Kw

W=0.020*2 =0.04 Kwh

Electric energy of second toaster in one day-

P=30W= 0.030 Kw

W=P.t = 0.030*2 = 0.060 Kwh

Total electric energy in one day=0.040+0.060 = 0.1 Kwh

In 30days,total electric energy = 0.1*30 = 3 Kwh

As we know, that 1 unit= 1 Kwh

So,total 3 unit consumed in 30 days.

Charge of 1 unit= Rs 10

So bill of the month= 3*10 = Rs 30