stephen buys x pencils and y notebook for his students each pencil costs $0.45 and each notebook costs $1.25 he buys a total of 210 pencils and notebooks for $142.50 which system of equation represent this situation A x+y= 0.45+1.25y=142.50 B x+y=142.50 0.45x+1.25y=210 C x+y =210 1.25x+0.45y=142.50 D x+y=142.50 1.25x+0.45y=210