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Lines a and b are parallel. what is the value of x? -5 -10 -35 -55

What adds to be the bottom number but also multiplies to be the top number with 8 on the bottom and 15 on top

Talia took the bus from her home to the bank and then walked back to her home along the same route. the bus traveled at an average speed of 40 km/h and she walked at an average speed of 5 km/h. to determine the time, x, that it took talia to walk home, she used the equation 40(0.9 – x) = 5x. the time of trip 2 is hours. the distance of trip 1 is km.