Teresa served 33 orders and Charlie served 24 orders and Justin served 96 orders
Solution:
Let "a" be the orders served by Teresa
Let "b" be the orders served by Charlie
Let "c" be the orders served by Justin
Teresa, Charlie, and Justin served a total of 153 orders
Therefore,
a + b + c = 153 -------- eqn 1
Justin served 4 times as many orders as Charlie
Orders served by Justin = 4( orders served by Charlie )
c = 4b ---------- eqn 2
Teresa served 9 more orders than Charlie
orders served by Teresa = 9 + orders served by Charlie
a = 9 + b ----------- eqn 3
Let us solve eqn 1 and eqn 2 and eqn 3
Substitute eqn 2 and eqn 3 in eqn 1
9 + b + b + 4b = 153
9 + 6b = 153
6b = 153 - 9
6b = 144
b = 24
Substitute b = 24 in eqn 3
a = 9 + 24
a = 33
Substitute b = 24 in eqn 2
c = 4(24)
c = 96
Thus Teresa served 33 orders and Charlie served 24 orders and Justin served 96 orders