Answer:
The equation is:
and the number is 72.
Step-by-step explanation:
We have to use mathematical notation to convert the given statement into an equation. As we don't know the exact value of number, we have to use a variable in place of the number.
Let x be the required number then
"A number decreased by 7"

"and then divided by 5"

" is 13."

For solving, multiplying both sides of equation by "5"

Adding 7 on both sides of equation

Hence,
The equation is:
and the number is 72.
Answer:
y=5x−z
Step-by-step explanation:
Step 1: Multiply both sides by y.
xy−5=yz
Step 2: Add -yz to both sides.
xy−5+−yz=yz+−yz
xy−yz−5=0
Step 3: Add 5 to both sides.
xy−yz−5+5=0+5
xy−yz=5
Step 4: Factor out variable y.
y(x−z)=5
Step 5: Divide both sides by x-z.
y(x−z)x−z=5x−z
y=5x−z
For a right triangle, the sum of the squares of two shorter side should be equal to the square of the third side. The calculations for each choices are shown below.
a. (5 mm)² + (12 mm)² = 169 mm² ; (13 mm)² = 169 mm² ; EQUAL
b. (20 mm)² + (48 mm)² = 2704 mm² ; (52 mm)² = 2704 mm² ; EQUAL
c. (6 mm)² + (8 mm)² = 100 mm² ; (10 mm)² = 100 mm² ; EQUAL
d. (11 mm)² + (24 mm)² = 697 mm² ; (26 mm)² = 676 mm² ; NOT EQUAL
Therefore, the answer is letter D.
<h3>
Answer: 78.6</h3>
Work Shown:

Multiply across the rows to form a third column. Example: 9*90 = 810 in the first row.

The values in the third column add to 810+1440+1050 = 3300
Divide this over the total number of people which is 9+18+15 = 42
The mean is 3300/42 =78.571 approximately which rounds to 78.6