Question

The total length of four blue banners and five yellow banners is 49 m. The total length of two blue banners and one yellow banner is 17 m. All banners of the same color have the same length. Find the length of each blue banner

Answer 1

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