It is a mixed fraction.
1-a, which may or may not be a fraction.
It is a fraction - which may be mixed or proper.
The process is still that of addition.
Assuming this is the answer to a division sum, that depends entirely what the divisor of the sum is.
The sum of a fraction? Well, to find the sum of the fraction all you do is divide both top and bottom numbers.
The sum is exactly and unequivocally 1.8
A mixed fraction.
It is a mixed fraction.
1-a, which may or may not be a fraction.
It is a fraction - which may be mixed or proper.
The sum is the answer for adding and the difference is the answer for subtracting...
A mixed number or mixed fraction.
The process is still that of addition.
This is called a mixed number.A mixed number is a number showing the sum of a whole number and a fraction
It is the same as for any other addition. The answer is the sum.
It depends on your level of numerical skill. You can convert the decimal to an approximate fraction and estimate the sum of the two fractions, or you can convert the fraction to an approximate decimal and estimate the sum of the two decimals or, if you are more able you just estimate their sum directly.