Assume that the baryonic mass M of a galaxy, such as the Milky Way, consisted purely of hydrogen when it was formed. In this case, all heavier elements must have formed from nuclear fusion in the interior of its stars. Assume further that the total luminosity L of the galaxy is caused by burning hydrogen into helium, and let this luminosity be constant over the total lifetime of a galaxy, which we assume to be $1010$ years. Assume also a constant baryonic mass$-$to$-$light ratio of M$\backslash /$L$=3$M$\_$Sun $\backslash /$L$\_$Sun. What is the mass fraction of helium that you would generate by the helium burning process and would it be large enough to explain the observed helium abundance of ~$27\%?$