Using solver for low uncertainty optimisation problems with detailed instructions

What kind of questions does it solve? We all know that sometimes we need to achieve certain goals, such as minimising the cost or maximising the profit. Then there're some restrictions like time, human resource, etc. If we use the math language to describe it, it could be: Minimise 10*X1+25*X2+32*X3 X1+X2+X3 =20 X1+X2 >=4 x2+X3 …