Answer:
153 adults and 168 children
Step-by-step explanation:
x - number of adults
y - number of children
[tex]\left \{ {{6x + 4y = 1590} \atop {x + y = 321}} \right.[/tex]
[tex]\left \{ {{6x+4y = 1590} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{6*(321 - y)+4y = 1590} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{1926 -6y+4y=1590} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{1926 -2y=1590} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{-2y=1590-1926} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{-2y=-336} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{y=168} \atop {x=321-y}} \right.[/tex]
[tex]\left \{ {{y=168} \atop {x=321-168}} \right.[/tex]
[tex]\left \{ {{y=168} \atop {x=153}} \right.[/tex]
Is it all clear?