You are provided with an arithmetic question. Your task is to compute the solution using the given arithmetic operations. The only arithmetic operators needed to answer the questions are'+'(addition) and'-'(subtraction). The answer should be correct to one decimal place.

[EX Q]: Joan has 47 green and 48 red marbles. Fred took 24 of Joan's greenmarbles. How many green marbles does Joan now have?
[EX A]: 23.0

[EX Q]: While making pastries, a bakery used 0.2 bag of wheat flour and 0.1 bag of white flour. How many bags of flour did the bakery use in all?
[EX A]: 0.3

[EX Q]: A construction company ordered 0.16 ton ofconcrete, 0.14 ton of bricks, and 0.5 ton of stone. How many tons of material did the company order in all?
[EX A]:
0.8