Question related to conjoint analysis
Here you have a possible answer (although I am not 100% sure about it):

You said Brand counts 50% and price 50%. We can consider that with higher brand utilities we get higher chance of buying, while with higher prices we get lower chance of buying the product. Following this idea, I made this equation in which both chances (of product A and B) should be equal, since it would lead us to an equilibrium in which it would be the same for the custumer to buy the product A or the product B:

$U_A - P_A = U_B - P_B$

We substitute according to our values:

$50 - 80 = 30 - x$

We simplify:

$-30 = 30 - x$

Again:

$-60 = -x$

And again:

$x = 60$

So 60\$ would be the price of indifference between product A and B. So we should make it a bit lower if we want people to buy product B: 59.9$, the correct answer of your problem.

I hope it helps.