Answer: 7 years
Step-by-step explanation:
let x be the age of Mary
so John's age will be 2x
the equation becomes
2x+x=21
3x=21
x=21/3
x=7
Answer:
Step-by-step explanation:
The relative speed of the two trains is the sum of the speeds they are traveling. (If you're on either of the trains, this is the speed you appear to be moving when you see the other train.) In our problem, the relative speed of the two trains is 70 mph + 60 mph = 130 mph. What if the trains were traveling in the same direction? Then we'd need to subtract the speed of the slower train from the speed of the faster train, and their relative speed would be 10 mph.
Her school is 2/3 miles away
2/3=4/6miles
So we need to find out how long it will take for her to run home from school...
School=4/6 miles
In 1 minutes she can run 1/6 miles
1min=1/6miles
In 2 minutes she can run 1/6+1/6 miles (1/6+1/6=2/6)
2min=2/6miles
3min=3/6miles
4min=4/6miles
It will take Erica 4 minutes to run 4/6 miles, so it'll take her 4 minutes to get home.
Answer:
x=-7
Step-by-step explanation:
9x + 16 = 4x - 19
Subtract 4x from each side
9x-4x + 16 = 4x-4x - 19
5x+16 = -19
Subtract 16 from each side
5x+16 -16 = -19-16
5x = -35
Divide each side by 5
5x/5 = -35/5
x = -7
The formula would be
A=p (1-r)^t
P 3400
R 0.02
Since it decreases every 20 years
From 2000 to 2040 it decreases 2 times so
T 2
A=3,400×(1−0.02)^(2)
A=3,265
It's c
