Peter is x years old and his sister is 5 years older. If the product of their ages is 84, form an equation in x and solve it to find peter's age

It appears that BEF is marked the same as BED.  BED is 180 - 90 - 50 which is 40.  angle BEF = 40.  If triangle BED is congruent to triangle BEF, which it is, then FE is the same measure as DE, and it just so happens that DE is marked congruent to CD which is 7.  Therefore, FE is also 7.