What is the maximum emf

In the circuit shown in the figure all the resistors are rated at a maximum power of 1.20W.
A link to the diagram is here: http://www.cramster.com/answers-sep-10/physics/maximum-emf-circuit-circuit-shown-figure-resistors-ra_928084.aspx

What is the maximum emf that the battery can have without burning up any of the resistors?

I keep getting 12.3 but this is not correct

added a bit the circuit is fairly simple if you understand things
yes the 20 ohm resistors above the 40 ohm ones are connected they are just a parallel arangement inside a parallel circuit .. so it looks complicated
but again just use ohms law on each parallel arrangment to find the total of the parallels then substitute that value in and then calculate the larger parallel

so with the big parallel this is what you do

the two 20 ohms are in parallel
this means the total resistance of the two is 10 ohms

because

1/Rt = 1/R1 + 1/R2 + 1/R3

if all R's are the same

then this becomes

1/Rt = 1/R + 1/R + 1/R
1/Rt = 3/R
inverting

Rt = R/3

so basically Rt of a parallel arangement of equal resistors is
Rt = R/n where n is the number of resistors

with two 20's
Rt = 20/2 = 10 ohms

we then replace the 2 20's with a single 10 ohm in the circuit and that produces
a simple parallel series arrangement


then you add all the resistors in series in each branch to make the branches a single resistor

so the ownly one with 2 resistors in a branch is the 10 and 2x 20 ohm branch

so since its value is now 10 and 10 ohm = 20 ohms now

so the parallel circuit becomes

25 ohms
15 ohms
20 ohms

now you just put in the formula and calculate it

1/Rt = 1/25 + 1/15 + 1/20
Rt in this case = 6.38





Rt = 126.38

I = V/Rt

this is the currrent running through each series component since it splits at the parallel circuits the power in them will be substantially lower