The Crews family went on a day trip to Nashville. For lunch they paid $7.50 for each adult meal and $5 for each child meal for a total of $65. For dinner the family paid $10.50 for each adult meal and $5 for each child meal for a total of $77. How many adults and how many children were on the trip?

Number of adult were on the trip = 4

Number of child were on the trip = 7

Step-by-step explanation:

Let the Number of adult were on the trip = x

Let the Number of child were on the trip = y

As given,

For lunch they paid $7.50 for each adult meal and $5 for each child meal for a total of $65.

⇒7.50x + 5y = 65            ...........(1)

Also,

For dinner the family paid $10.50 for each adult meal and $5 for each child meal for a total of $77.

⇒10.50x + 5y = 77            ...........(2)

Now,

Subtract equation (2) from equation (1) , we get

10.50x + 5y  - ( 7.50x + 5y ) = 77 - 65

⇒10.50x + 5y  - 7.50x - 5y  = 12

⇒10.50x - 7.50x  = 12

⇒3x = 12

⇒x = = 4

⇒x = 4

Now,

Put the value of x in equation (2) , we get

10.50(4) + 5y = 77

⇒42 + 5y = 77

⇒5y = 77 - 42

⇒5y = 35

⇒y = = 7

⇒y = 7

∴ we get

Number of adult were on the trip = x = 4

Number of child were on the trip = y = 7

The solution is in the following image

The answer is in the image 

The answer is in the image 

Speed=Distance/time

Here,

distance=15m

time=1sec

speed=15/1=15m/sec

Distance=Speed*time

time=15min=15*60sec=900sec

Distance travelled in 15 min=15*900=13,500m

=13500/1000 km=13.5Km

The answer is in the image 

The answer is in the image 

Let the father's age be x and son's be y

10 years before-

Father age=x-10

sons age=y-10

Given,

x-10=10(y-10)

x-10=10y-100

Given present age of father=40

therefore,

x=40

40-10=10y-100

10y-100=30

10y=130

y=130/10

y=13

Therefore present age of son=13years

We can put the numbers in ascending order-

36, 38, 39, 39, 40, 47, 48, 51

Range=max-min

          =51-36

          =15

Weight of adult elephant = 24,000 pounds

Weight of baby elephant = 260 pounds

Difference between weight = 24,000 - 260 = 23,740

Adult elephant weights 23,740 pounds more