[tex]x-length\ of\ blue\ banner\\y-length\ of\ yellow\ banner\\\\ \left \{ {{4x+5y=49} \atop {2x+y=17}} \right. \\\\From\ second\ equation:\\y=17-2x\\\\Substitute\ to\ first\ equation:\\4x+5(17-2x)=49\\4x+85-10x=49\\4x-10x=49-85\\-6x=-36\ \ \ \ |:-6\\x=6\\\\Length\ of\ each\ blue\ banner\ is\ 6m.[/tex]
