To calculate 40 percent of the number 1380, we need to create a ratio from which we can easily determine the value we are looking for. We first create two simple equations with data we know. 1380 equals 100%, so we can save it as 1380 = 100% The value we are looking for can be called x We now know that x is 40 of the output value, so we can write it as x = 40. So we have two simple equations: 1) 1380=100% 2) x=40% When we compare these two equations, we get: 1380/x=(100%)/(40%) Now we just have to solve the simple equation.
