At joe's cafe 1 cup of coffee and 3 donuts is $4.10 and 2 cups of coffee and 2 donuts is $4.60, how much is 1 count? 1 cup of coffee?

C + 3d = 4.10multiply by -2
2c + 2d = 4.60

-2c - 6d = - 8.20 (result of multiplying by -2)
2c + 2d = 4.60
add
     -4d = - 3.60
        d = -3.60 / -4
        d = 0.90 < cost of 1 doughnut

c + 3d = 4.10
c + 3(0.90) = 4.10
c + 2.70 = 4.10
c = 4.10 - 2.70
c = 1.40 < cost of 1 coffee