Answer:
25 black keys
Step-by-step explanation:
Let the number of requires black keys = 'x'
White key : Black keys = 7 : 5
7 : 5 :: 35 : x
Product of extremes = product of means
7 *x = 35 * 5
x = 
x = 5 *5
x = 25
<span>So
I only have ones, tens and hundreds block. I need to find a way how can I fit
the given number 1 718.
=> Since I have hundreds block, I can divide 1 718 by 100
=> 1 718 / 100, how many 100s are there in 1 718
=> 17 hundreds
=> now we only have 18 left
=> 18 / 10, how many 10s are there in 18
=> 1 tens
=> Now we only have 8 left
=> 8 / 1, how many ones are there in 8
=> 8
=> 17 hundreds, 1 tens, and 8 ones.</span><span>
</span>
4 - 5x = 59
Subtract 4 from both sides:
-5x = 55
Since x is being multiplied by -5, the next step is to divide both sides by -5.
The sum of a and b will be the coefficient of the x term of the trinomial. This can be seen below.
(x + a)(x + b)
= x² + bx + ax + ab
= x² + (a+b)x + ab
x is being multiplied by both a and b individually and the products are being added, so sum of a and b appears as the coefficient of x term.
Thus the answer to this question is option C
