Hello! :)
Answer:

as a mixed number:
Divide 2 from 7 and find the remainder:
7 ÷ 2 = 3 R 1.
An improper fraction in mixed form has the quotient as the coefficient, and the remainder over the fraction. Therefore:

Sub x = 2-y^2 to Q, we get:
Q = 3(2-y^2)*y^2
let y^2 = k
Q = 3(2-k)k = 3(2k-k^2)
2k-k^2 has a max when k = 1
Then y^2 = 1 -> y = 1 or -1
Okay so the value of X is 9x^2/7
Answer:
Let the marked price be x
Discount % = 10%
Discount = 10\% \times x = 0.1x10%×x=0.1x
Cost after discount = x-0.1x = 0.9x
10%vat is charged on it
Cost including VAT = 0.9x+0.1(0.9x)=0.99x0.9x+0.1(0.9x)=0.99x
We are given that it's price became rs 1672
So, 0.99x = 1672
x=\frac{1672}{0.99}x=0.991672
x=1688.88
Discount = 0.1x=0.1(1688.88)=168.888
Hence The discount