Ralph is 3 times as old as sara. in 4 years, ralph will be only twice as old as sara will be then. find ralph's age now.

if x represents sarah's age now, which of the following expressions represents ralph's age in four years?

Step-by-step explanation:

Since, x represents Sarah's present age  then

According to question

Ralph is 3 times as old as Sara.

that is present age of Ralph = 3x

After 4 years age of Sara will be x + 4

and age of Ralph will be 3x + 4.

According to question,

In 4 years, Ralph will be only twice as old as Sara will be then.

⇒ 3x + 4 = 2( x + 4)

Solving for x, we get,

⇒ 3x + 4 = 2 x + 8

⇒ 3x -2x = 8 - 4

⇒ x = 4.

Thus, Sara present is 4 years and Ralph present age is 3x = 12

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.