Equation 2:
by2  -  8y + 4 = 0
One of the roots of equation 2 is 2/3. So,
b(2/3)2  -  8(2/3) + 4 = 0
4b/9 = 4/3
b = 3
Now, 3y2  -  8y + 4 = 0
3y2  -  6y  -  2y + 4 = 0
3y(y  -  2)  -  2(y  -  2) = 0
(y  -  2)(3y  -  2) = 0
y = 2, 2/3
The ratio of highest root of equation 1 to the highest root of equation 2 is 7: 4. So,
Highest root of equation 1 = 2 * 7/4 = 7/2
Now, Equation 1: ax2  -  9x + 7 = 0
a(7/2)2  -  9(7/2) + 7 = 0
49a/4 = 49/2
a = 2
So, 2x2  -  9x + 7 = 0
2x2  -  7x  -  2x + 7 = 0
x(2x  -  7)  -  1(2x  -  7) = 0
(2x  -  7)(x  -  1) = 0
x = 7/2, 1
(a + b)2x2 + (3ab + 1)x  -  6 = 0
(2 + 3)2x2 + (3 * 2 * 3 + 1)x  -  6 = 0
25x2 + 19x  -  6 = 0
25x2 + 25x  -  6x  -  6 = 0
25x(x + 1)  -  6(x + 1) = 0
(x + 1)(25x  -  6) = 0
x = -1, 6/25