Add up to example sentences

Let us illustrate this by taking addition of HBr to symmetrical and unsymmetrical alkenesHydrogen halides (HCl, HBr,HI) add up to alkenes to form alkyl halides.Hydrogen halides (HCl, HBr,HI) add up to alkenes to form alkyl halides.Use of poor quality of coal, kerosene and firewood as fuel for domestic purposes add up to this problem.Therefore wages, interest, profits and rents paid out by the firm must add up to the value added of the firm.