Solve as a whole number x + 3y = 1
-3x - 3y = -15

Hii, hope this helps

Y= - 2

X = 7

The answer is in the image 

The answer is in the image 

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

tip=18% of 75.45

     =18/100 * 75.45 = $13.581

Tip = $13.581

The solution is given below

The answer is in the image 

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