Answer:

Step-by-step explanation:
A road is perpendicular to a highway leading to a farmhouse d miles away.
An automobile passes through the point of intersection with a constant speed
= r mph
Let x be the distance of automobile from the point of intersection and distance between the automobile and farmhouse is 'h' miles.
Then by Pythagoras theorem,
h² = d² + x²
By taking derivative on both the sides of the equation,




When automobile is 30 miles past the intersection,
For x = 30

Since 
Therefore,


The length of the side of the original square is 7cm
Step-by-step explanation:
108-ambulance
100- police
1098-child laber
Answer:
The number is 12
Step-by-step explanation:
Let x = number
2x+16 = 40
Subtract 16 from each side
2x+16-16 =40-16
2x = 24
Divide by 2
2x/2 =24/2
x = 12
Only once, any number higher will pass it