Answer: Hi! when someone says that the odds on (against) your bet are 4 to 7, means that you have 4 chances to lose, and 7 to win.
then if 4 + 7 = 11 = 100%
4/11*100% = 36.36%
and 7/11*100% = 63.63%
You can notice that the probability for a win is bigger than the probability for a loss, so the amount earned will be less than the bet.
So you have a 63% chances of winning
then, if you bet 70$, you will win 70$*4/7 = 40$
so the total return is 70$ + 40$ = 110$