Over the last 3  evenings, Keisha received a total of 81  phone calls at the call center. The first evening, she received 6  fewer calls than the second evening. The third evening, she received 3  times as many calls as the first evening. How many phone calls did she receive each evening

Answer:First: 15Second: 21Third: 45Step-by-step explanation:In order to create the equation we need to represent the evenings with an alebraic term, in thsi case we are going to represent the second evening with an XSecond evening:xThe first night she got 6 fewer calls than the second: Second-6=x-6The third night she received 3 times the first: 3(first night)=3(x-6)The equation is First Night plus second night plus third night equals 81.[tex]First+second+third=81\\x+(x-7)+3(x-6)=81\\x+x-7+3x-18=81\\5x=81+21+6\\5x=105\\x=\frac{105}{5} \\x=21[/tex]So the first evening he received 15 calls, the second he received 21 and the third one he received 45.