+770 I'll just assume you need help on BOTH the problems :D
For (7)
This is a problem of ratios. The ratio of an object's height to its shadow length will be the same at the same time.
The ratio between the person's height and their shadow length is 6 : 10, or 3 : 5.
Let's say the tower's height is T.
We know that:
T : 400 ft (Shadow length) = 3 : 5
This also means that T/400 = 3/5
We can cross-multiply to get 5T = 1200
Now we can simply divide to get T = 1200 / 5 = 240 ft, which is the 4th option :D
For (8)
Another problem on ratios :) Here the ratio between the height and the width of the photograph is being considered.
The ratio between the height and width is 4 : 6, or 2 : 3.
Let's say the future height of the photograph is H.
We know that:
H : 10 = 2 : 3
This also means that H/10 = 2/3
Now we can cross-multiply to get 3H = 20
Then we can divide to get H = 20/3 = 6.666 in. forever! (rounded to 6.7, which is the 4th option agan!) :D
