The cost of having photos taken includes a sitting fee and $12 for each portrait. the cost of 3,6, and 9 photos respectively is $51 ,$87, and ,$123. what is the sitting fee ? i have to uses the formula y=mx+b to solve

The sitting fee is 15 dollars

Step-by-step explanation:If you were to use the formula y=mx+b then the starting equation would be y=12x+b. It already gave you the cost for the amount of photos respectively so 51=12(3)+b. 12 times 3 equals 36 and 51 minus 36 equals 15. The same way would be used for 87 dollars and 123 dollars while using the amount of photos respectively. 87=12(6)+b. 12 times 6 equals 72. 72 plus 15 equals 87. 123=12(9)+b. 12 times 9 equals 108. 108 plus 15 equals 123. Therefore the sitting fee is 15. (51=12(3)+15, 87=12(6)+15, 123=12(9)+15)

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