x for how much one cookie costs and y for how much one doughnut costs 6x+4y=3.5 12x+5y=5.23
solve by substitution: (elimination would work too) 4y=3.5-6x y=0.875-1.5x 12x+5(0.875-1.5x)=5.23 12x+4.375x-7.5x=5.23 4.5x=0.855 x=0.19 now use x to solve for y: 6(0.19)+4y=3.5 1.14+4y=3.5 2.36=4y y=0.59
