Question 1176894
{{{x }}}is the number of teachers who registered early
let {{{y }}}be the number of teachers who registered  regularly

{{{x +y=1200}}}
{{{y=1200-x}}}.....eq.1

a.

 If {{{x }}}is the number of teachers who registered early, express the total fees collected in terms of x.

{{{2000x}}}

b. 
If {{{2825000}}} pesos were collected, how many of each type registered?

{{{2000x+2500y=2825000}}}..........substitute {{{y}}} from eq.1


{{{2000x+2500(1200-x)=2825000}}}
{{{2000x+3000000 - 2500x=2825000}}}
{{{3000000 - 500x=2825000}}}
{{{3000000 - 2825000=500x}}}
{{{175000=500x}}}
{{{x=175000/500}}}
{{{x=1750/5}}}
{{{x=350}}}-> the number of teachers who registered early

go to eq.1

{{{y=1200-x}}}.....eq.1, substitute {{{x}}}
{{{y=1200-350}}}
{{{y=850}}}-> the number of teachers who registered regularly


the total fees collected  from teachers who registered early:{{{2000x=2000*350=700000}}}

the total fees collected  from teachers who registered regularly:{{{2500y=2500*850=2125000}}}



check total: 
{{{700000+2125000=2825000}}}