The school concert raised $1360 from the sale of 400 tickets. if adult tickets cost $5 and student tickets $3, how many student tickets were sold?

You would use a system of equations.
A= adult tickets sold
S= student tickets sold
A+S=400
5A+3S=1360

-3(A+S=400)= -3A-3S=-1200 +
5A+3S=1360 =
2A = 160 so A=80

now when you plug 80 into the original equation you get 80 + S = 400 so S=320

80 Adult tickets were sold and 320 student tickets were sold.