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What is sin 7x/4 ? i need on this urgent trig

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

What is the solution to the system of equation graphed belowa.(0,-4)b.(2,5),1),-3)