You'd really just have to simply divide the two decimals. That's it. So you would divide 3.480 and 0.29 (if you want, you can use a calculator, otherwise, maybe search it up online how to divide decimals. It's really the same as dividing normal numbers, except you've got to move around the decimal point and etc.
3.340 ÷ 0.29 = 12
(Multiply the opposite to check your answer if needed.)