Hey there! :)
Since 0.8 is less than 1, you can cross out every fraction greater than 1. If the numerator(top number) is greater than the denominator(bottom number), it is greater than 1
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You can cross out 12/7 because it is greater than 1.
That leaves you with 3 choices.
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Now, divide the numerator by the denominator to change all 3 fraction to decimal.
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7 ÷ 8 = 0.875
3/6 = 0.5
4/5 = 0.8
A. 12/7 x
B. 7/8 x
C. 3/6 x
D. 4/5 ✔
Your answer is the last choice.
Hope this helps :)