Ahigh school graduating class is made up of 511 students. there are 165 more girls than boys. how many boys are in the class?

X=number of boys.
y=number of girls.

We can suggest this system of equations:

x+y=511
y=x+165

We can solve this system by substitution method.

x+(x+165)=511
2x=511-165
2x=346
x=346/2
x=173

y=x+165
y=173+165
y=338

there are 173 boys in the class.