What is the value of x in the proportion x+1/x+3=15/21
i need help can some one help me with the steps

Question

What is the value of x in the proportion x+1/x+3=15/21
i need help can some one help me with the steps

anonymous · Answer

you could try cross multiplying

$$\frac{ a }{ b } = \frac{ c }{ d } \rightarrow ad = bc$$

in this case:

$$\frac{ x + 1 }{ x + 3 } = \frac{ 15 }{ 21 } \rightarrow (x+1) * 21 = (x + 3) * 15$$

anonymous · Answer

so it would be 3x=1x ?

anonymous · Answer

well we have

(x + 1) * 21 = (x + 3) * 15

this is the same as

21x + 21 = 15x + 45

anonymous · Answer

i have no idea what im doing sorry

anonymous · Answer

you have to solve this algebra problem for x:

21x + 21 = 15x + 45

anonymous · Answer

can you do a example problem ?

anonymous · Answer

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