Answer:
D
Step-by-step explanation:
We can test each pair making each ratio into its simplest form.
For A 2/3 is already in its simplest form and 9/15=3/5. they are not equivalent.
For B, 5/8 is already in its simplest form and 15/21=5/7. they are not equivalent.
For C, 3/12=1/4, and 6/18=1/3. They are not equivalent.
For D, 4/10=2/5, and 12/30=2/5. They are equivalent.
Answer:

Step-by-step explanation:
<h2><u>IdEnTiTy UsED</u></h2>

1)

=(x-5)²
2)



3)

= (1+x)²
So r+c=42
c=4+r
subsitute c=4+r for r in r+c=42
r+4+r=42
add like terms
2r+4=42
subtract 4 from both sides
2r=38
divide both sides by 2
r=19
rob=19
subsitute r=19 for r in c=4+r
c=19+4
carly=23