
Andy C. answered 09/16/17
Tutor
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Math/Physics Tutor
Let X be the number of $10 tickets (because X is the roman numeral for 10)
Let J be the number of $20 tickets (because J stands for Jackson and Andrew Jackson is on the $20 bill)
Let T be the number of $30 tickets
X + J + T = 547 <--- 547 tickets were sold
J = X + 150 <-- there were 150 more twenty dollar tickets than $10 tickets
10X +20J +30T = 9900 <--- total sales were $9900
Substituting J=X+150 into
equations 1 and 3, the system becomes:
X + X+150 + T = 547
10X + 20(X+150) + 30T = 9900
combining like terms and distributing:
2X + 150 + T = 547
10X + 20X + 3000 + 30T = 9900
Finally:
2X + T = 397
30X + 30T = 6900
Dividing the second equation by 30 and
solving the first equation for T:
T = 397 - 2x
X + T = 230
By substitution:
X + 397 - 2X = 230
0 = 230 - X - 397 + 2X
0 = X - 167
X = 167
T = 397 - 2X = 397 - 2(167) = 63
Finally using the original first equation
X + J + T = 547
167 + J + 63 = 547
J = 547 - 167 - 63 = 317
167 x $10 + 317 x $20 + 63 x $30 = $9900