math help

What is 78/10 + 2/4?

What is 78/10 + 2/4?

This is how we add

78
10
+
2
4

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 78 by 4, and get 312, then we multiply 10 by 4 and get 40.

78/10 times 4

Do the same for the second term. We multiply 2 by 10, and get 20, then multiply 10 by 4 and get 40.

2/4 times 10

The problem now has new fractions to add:

312
40
+
20
40

Step 2

Since our denominators match, we can add the numerators.

312 + 20 = 332

The sum we get is

332
40

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:

332
40
÷ 2 =
166
20

Now, try the same number again.

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

166
20
÷ 2 =
83
10

Now, try the same number again.

Nope. Try the next prime number, 3...

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

No good. 11 is larger than 10. So we're done reducing.

Congratulations! Here's your final answer to 78/10 + 2/4

78
10
+
2
4
=
83
10
© 2014 Randy Tayler