4y = -23 + 39
4y = 16
y = 4
Sub y = 4 into equation 2
7x + 6(4) = -39
7x + 24 = -39
7x = -39-24
7x = -63
x = -9
x = -9
y = 4
Answer:

Step-by-step explanation:
The surface area of a square pyramid is the sum of the area of the squared base + 4 times the area of each triangular face, therefore:

where:
is the area of the base, where
L is the length of the base
is the area of each triangular face, where
h is the height of the face
Substituting,

For the model in this problem,
L = 12
h = 8
Therefore, the surface area here is:

He needs it 4 inches longer because 4 ft is 48 inches.
Answer:
Beginning in the 6th century BC with the Pythagoreans, the Ancient Greeks began a systematic study of mathematics as a subject in its own right with Greek mathematics. Around 300 BC, Euclid introduced the axiomatic method still used in mathematics today, consisting of definition, axiom, theorem, and proof.
Step-by-step explanation:
The first recorded zero appeared in Mesopotamia around 3 B.C. The Mayans invented it independently circa 4 A.D. It was later devised in India in the mid-fifth century, spread to Cambodia near the end of the seventh century, and into China and the Islamic countries at the end of the eighth.