Hi Deynaliz U.
Given
m∠EFG = 5n + 23
m∠GFH = 3n + 13
We want to find the m∠EFG and m∠GFH
Just looking at the description of the angles, it appears that FG or GF is a common line in side a larger angle EGH and the angles given are adjacent angles. That said draw yourself a picture. Your info does not say that these are equal, complementary or supplementary angles.
Looks like a bit more data is needed