A bridge is built in the shape of a semielliptical arch. The bridge has a span of 80 feet and a maximum height of 30 feet. Choose a suitable rectangular coordinate system and find the height of the arch at a distance of 30 feet from the center.

b = 3/8a

Step-by-step explanation:

The following table shows a proportional relationship between A and B.

a         b

8        3

24     9

40    15

1/4

Let's find the constant of proportionality.

In the proportional relationship between aaa and bbb, one constant of proportionality is the number we multiply by aaa to get bbb.

a\, \times\, ?=ba×?=b

2/4

a        b

8        3   8 × 3/8=3

24     9    24×3/8=9

40    15   40×3/8=15

The constant of proportionality is 3/8. This means we can multiply 3/8 by a to get b.

Now, let's represent that as an equation.

b= constant of proportionality × a

b = 3/8a

One correct equation is b=3/8a

hi. So I did copy this answer from Khan Academy, but I thought it would help you guys so I put it on here.  -Alicia Dugaw