Let mass of electron is half, mass of proton is two times and mass of neutron is three fourth of original. Then find out new atomic wt. of $O^{16}$ atom

Mass of electron is negligible

O¹⁶ contains protons = 8 neutrons = 8 

Proton mass doubled and neutron mass become $\frac{3}{4}$th 

mass number = $8\times 2 +\left(8\times \frac{3}{4}\right)=22$

Increase in % =  $\frac{22-16}{16}\times 100=37.5$