Question

Please help me with the question

Answer 1

A) 5 black keys : 7 white keys
b) 5*5 black keys : 7*5=35 white keys
There are 25 black keys for every 35 white keys.
c) (5+7)x = 240 keys where x is the number of octaves, 240/12=20
20*5=100 black keys

Answer 2

Answer:

6a.) 5:7

6b.) 25 black keys

6c.) 100 black keys and 140 white keys

Step-by-step explanation:

It's simple

6a.) The ratio of black keys to white keys is 5:7. You count the black keys and count the white keys. 5 is the black keys and 7 is the white keys

6b.) Now that you have your ratio of 5:7, you can compare it to 35 white keys. Remember, 7 is the white keys. You do not know how many black keys there are in the new ratio. So your problem would be 5:7 = x:35 [x representing the black keys.] You could then cross multiply to get 7x = 175. Divide both sides by 7 to get x = 25. Therefore, there are 25 black keys and 35 white keys. You could also just divide 35 ÷ 7 = 5, then multiply 5 × 5 to get 25 black keys

6c.) Here they are actually giving the total amount of keys instead of the white keys. But we already know that for every 5 black keys, there are 7 white keys. Let's just add 5 + 7 to get 12 total keys. Then, divide 240 ÷ 12 to get 20. Alright, now let's multiply our original ratio (5:7) by 20

5 × 20 = 100 black keys

7 x 20 = 140 white keys

100 + 140 = 240