(1.20+3/9)+5.98

To solve this expression, we can start by simplifying the fraction 3/9, which is equal to 1/3.

So, the expression becomes:

(1.20 + 1/3) + 5.98

Next, we need to convert the mixed number 1.20 into an improper fraction.

1.20 = 1 + 0.20 = 1 + 20/100 = 1 + 1/5 (since 20/100 simplifies to 1/5)

Now, the expression becomes:

(1 + 1/5 + 1/3) + 5.98

To add the fractions, we need to find a common denominator. In this case, the common denominator is 15.

So, the expression becomes:

(15/15 + 3/15 + 5/15) + 5.98

Now we can add the fractions:

(23/15) + 5.98

To add the fractions to the mixed number, we need to convert it into an improper fraction.

5.98 = 5 + 0.98 = 5 + 98/100 = 5 + 49/50 (since 98/100 simplifies to 49/50)

Now, the expression becomes:

(23/15) + (5 + 49/50)

To add the expressions, we can find a common denominator, which is 50.

(23/15) + (250/50 + 49/50)

Now we can add the fractions:

(23/15) + (299/50)

To add these fractions, we need to find a common denominator, which is 150.

(690/150) + (447/150)

Now we can add the fractions:

(690 + 447)/150 = 1137/150

Finally, we can simplify the fraction.

1137/150 = 7.58

So, the final answer is 7.58.