Answer:
We know that:
Energy released by fusion of hydrogen in 1 liter of solution A = 7.6x10^10 J
Energy used daily in a certain family home = 3x10^4 J
(you did not write the units, so i suppose that are the same in both cases)
Then, if x is the number of liters of solution A used, the energy produced will be:
E(x) = x*7.6x10^10 J
And we want this equal to 3x10^4
then:
E(x) = x*7.6x10^10 J = 3x10^4 j
now we solve this for x.
x = (3x10^4 j)/(7.6x10^10 j) = 3.9x10^-7
Then you need to use 3.9x10^-7 L of solution a.
