Question 258824
17x+8y=191 multiply by 15.
12x+15y=219 multiply by -8 & add.
255x+120y=2,865
-96x-120y=-1,752
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159x=1,113
x=1,113/159
x=$7 is the hourly rate for daytime hours.
17*7+8y=191
119+8y=191
8y=191-119
8y=72
y=72/8
y=$9 is the hourly rate for nightime hours.
Proof:
12*7+15*9=219
84+135=219
219=219