Helo any help please?

5,600 x 10^3 = a) 560 b) 5,000,600 c) 5,600,000 d) 56,000

During a bike challenge riders have to collect various colored ribbons each 1/2 mile they collect a red ribbon each eighth mile they collect a green ribbon and each quarter mile they collect a blue ribbion wich colors of ribion will be collected at the 3/4 markrer

Solve the given system of equations. 2y= -x+9 , 3x-6= -15