The Q30X program and the Intensity program are both effective because the average participant 1-mile run time was reduced for each program, but the Intensity program is the more effective program because it yielded a greater decrease in the average participant 1-mile run time.
If you expand out the brackets you get this,
(4+5i)(a+2i) = 4a + (5a)i + 8i - 10
The -10 comes from 5i * 2i.
Squaring i becomes -1.
Let's group the real stuff together,
and imaginary separately,
(4a - 10) + (5a + 8)i
For this to be purely imaginary,
the real part needs to be zero.
Therefore 4a - 10 = 0
Solve for a.
To get 10% of your calories from polyunsaturated fats you would need to eat 200 calories worth. So 1 serving of walnuts would give you 180 calories. So one serving of walnuts would be 9% of your daily calories.