Question 198283
Your first part was almost right.
{{{x+y+38}}}--->{{{x+y=38}}}
All houses (x) and houses (y) make 38 houses.
Second part was perfect
{{{175,000x+200,000y=7,200,000}}}
But lets get rid of the huge parts
{{{175x+200y=7200}}}

Solve.
Substitution
{{{x+y=38}}}--->{{{x=38-y}}}
{{{175(38-y)+200y=7200}}}
{{{6650-175y+200y=7200}}}
{{{25y=550}}}
{{{y=22}}}
Resubstitute
{{{175x+200(22)=7200}}}
{{{175x+4400=7200}}}
{{{175x=2800}}}
{{{x=16}}}
Check
{{{22+16=38}}}
{{{38=38}}}
Done