PLS PUT THE CORRECT ANSWER AND SHOW HOW YOU DID IT PLS :(

5-7(9b-3d). D=3 b=9

Subsitute (nothing hard)

5-7(9*9-3*3)

Combine

5-7(72)

Distibute left to right

-7*72= -504

5-504

-499

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4