In order to solve this we must first,
Subtract both sides of the equation by 10,
y-10=1/2x
Now we have to multiply both sides by 2 so that only x is left.
2y-20=x
Therefore, x=2y-20
1 pound of rice costs $3.45
1.2 pounds of rice costs x
Set up the proportion
1 / 1.2 = 3.45 / x Cross Multiply
x = 1.2 * 3.45 Combine
x = $4.14 Answer