To solve you can use 10% of 50, to find 10% of any number simply move the decimal one point to the left. So in this case, 50.0 becomes 5.0. Therefore, 5 is 10% of 50. Then multiply 5 times 4 to get 20. Since 5 is 10% of 50, 20 is four 10% of 50, or simply 40%.
