math help

What is 80/2 + 3/5?

What is 80/2 + 3/5?

This is how to add

80
2
+
3
5

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 80 by 5, and get 400, then we multiply 2 by 5 and get 10.

80/2 times 5

Do the same for the second term. We multiply 3 by 2, and get 6, then multiply 2 by 5 and get 10.

3/5 times 2

The problem now has new fractions to add:

400
10
+
6
10

Step 2

Since our denominators match, we can add the numerators.

400 + 6 = 406

This yields the answer

406
10

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

406
10
÷ 2 =
203
5

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

No good. 7 is larger than 5. So we're done reducing.

There you have it! Here's the final answer to 80/2 + 3/5

80
2
+
3
5
=
203
5
© 2014 Randy Tayler