Why cant i do a simple math equasion

bets to $4 sb folds we 3b to $12 were risking $12 to win $4.5 how do i calculate the % that the 3 bet needs to work to be profitable.

Using a calc so make it simple as possible please

12 / (12 + 4.5) = 12 / 16.5 = 72.727%

So it has to work at least 72.727%.

Simple enough?

Ye cheers. damn im dumb

uberkuber's result is correct if by 'needs to work' OP meant he had air and would win only if villain folded. Otherwise, it gets more complicated as shown below:

The pot before villain bets is assumed to be 1.5 (blinds). Villain raises to 3 and hero (bb) raises to 12. If villain folds, hero wins 4.5. If villain calls he adds 10 to pot to be won by hero. With a win, hero wins 4.5+10=14.5 and with a loss, he loses 12.

The showdown EV equation with fold equity (fe) and showdown equity of eq is:

EV = fe*4.5 + (1-fe)*(eq*14.5-(1-eq)*12)

If fe is 0, break even equity is 12/26.5 = 45.3%. If fe = 20%, break even equity is 41%. At 50% fold equity, break even equity is 28.3%.

Note if we set eq to 0 in the EV equation we get needed fold equity of 12/16.5 as uber showed

how would you find fe?

By estimating, combinatorics or using a program like Flopzilla.

E.g. if you think villain will fold to a turn x/r with everything worse than an overpair you need to work out villains total range and how much of his range is overpair+. The remainder is the fold equity.