For the given ratios to be equivalent, we need them to be proportional. First we will write them as fractions and then we can set them equal to one another. Then we will have a proportion that we can solve for x.
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First Ratio: & 1:8 ⇒ 1/8 [0.8em]
Second Ratio: & 4:x ⇒ 4/x [0.8em]
Proportion: & 1/8=4/x
To solve the proportion, we will use the Cross Products Property.