In addition to taste buds, what should also guide our eating habits?

Food doesn't have flavor without saliva if that's what you're asking. However, what should guide your habits is how you personally feel and what is healthy. If you feel hungry, go for it, but make sure you're eating a healthy amount. Not too much but not too little.

      x/140 = 25/100

we need to find the x to find the x multiply 140 and 25

and what do you get 3500.   and what is 3500 divided by 100

= 35