Answer: First option
Step-by-step explanation:
You have the quadratic equation given in the problem:

To find an equivalent expression you cacn factorize. Find two numbers whose sum is -13 and whose product is -30.
These numbers would be -15 and 2.
Therfore, you obtain the following equivalent expression:

If you don't want to apply the method above, you can use the quadratic formula:

Where:

When you susbstitute values you obtain that:

Then you can rewrite the equation as 
Since sale is 40% so the price is 60%
61*(60%) = 36.6
the tax is 5%
so the price after tax is: 36.6 * (1 +5%) = $38.43
Answer:
6 kg
Step-by-step explanation:
Given is weight of an object directly varies with the mass of the object .
Let the constant of proportionality be k
So,
Weight = K×(mass of the object)
For an object , weight = 45 N
mass = 9 kg
So , 45 = K×9
K = 5.
Now, for the other object ,
Weight = 30 N. K = 5 (as obtained above)
So, 30 = 5×(mass of the object)
mass of the object = 6 kg.