15 arches decreased by 80%

If it decreases by 80٪, then only 20٪ remains.

15×20٪=15×20/100=15×0.2=3

3

3 arches

Step-by-step explanation:

Given

15 arches decreased by 80%.

First get 80% of 15 arches

That’s 80%/100% x 15

0.8 x 15

12 arches

Now subtract 12 arches from 15 arches to get the decrease

Decrease = (15 - 12) arches

= 3 arches

Therefore, 80% decrease of 15 inches is equal to 3 arches

y = - 6

step-by-step explanation:

given the point (- 2, y) lies on the graph then it is a solution of it's equation.

substitute x = - 2 into the equation for value of y

y = 3(- 2) = 3 × - 2 = - 6

the point on the graph is (- 2, 6)

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.