To find how much you paid for the tip, take the price of the meal and multiply by the tip rate (presented as a decimal)
so 15×.2 will equal what tip you pay
then just add that to the price of the meal
A=3B
4.35A+5.40B=780.95
Substitute 3B into A for the second equation:
4.35(3B)+5.40B=780.90
13.05B+5.40B=780.90
18.45B=780.90
B=42.33
Plug into equation 1:
A=3B
A=3(42.33)
A=126.98

//Add 6 to both sides:

//Multiply by -1 on both sides:

Multiply by 3 on both sides:

Divide by 4 on both sides:

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Answer: x = 15 (Answer C)-----------------------------------------