c = child tickets
a = adult tickets
Solve this with the substitution method.
Make two equations:
6.30c + 9.90a = 1,246.50
c + a = 159
Solve for c.
Subtract 9.90a from both sides.
6.30c = 1,246.50 - 9.90a
Divide both sides by 6.30.
c = 197.86 - 1.57a (rounded to hundredths)
Plug c into second equation.
197.86 - 1.57a + a = 159
Combine like terms.
197.86 - 0.57a = 159
Subtract 197.86 from both sides.
-0.57a = -38.86
Divide both sides by -0.57.
a = 68.18
round up to ones: 68
[tex]\boxed {68~adult~tickets}[/tex] were sold.
