# Saxon 87 math problem help needed

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My ds is on lesson 74, lesson practice problem "c".

C. Eighty is 0.4 of what number?

The method they want him to use is :

80 = 0.4 x Wn

80/0.4 = 0.4 x Wn/0.4 ( I couldn't type it as a fraction)

200 = Wn

DS's method is :

80 = 0.4 of X

0.4 = 2/5

(80 divided by 2) 5 = 200

My question is : Is there a reason behind Saxon having him do this problem a specific way or can ds use his method? Ds says that the Saxon method is very confusing to him. I'm not sure what to do.

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My ds is on lesson 74, lesson practice problem "c".

C. Eighty is 0.4 of what number?

The method they want him to use is :

80 = 0.4 x Wn

80/0.4 = 0.4 x Wn/0.4 ( I couldn't type it as a fraction)

200 = Wn

DS's method is :

80 = 0.4 of X

0.4 = 2/5

(80 divided by 2) 5 = 200

My question is : Is there a reason behind Saxon having him do this problem a specific way or can ds use his method? Ds says that the Saxon method is very confusing to him. I'm not sure what to do.

There is no difference - he is doing exactly the same thing. Whether he calls the fraction 0.4 or 2/5 makes no difference.

He should, however, learn to properly write out his procedure, using a variable for the unknown quantity:

80 = 0.4 of X = (2/5) X

80/ (2/5)=X

X=200

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There is no difference - he is doing exactly the same thing. Whether he calls the fraction 0.4 or 2/5 makes no difference.

He should, however, learn to properly write out his procedure, using a variable for the unknown quantity:

80 = 0.4 of X = (2/5) X

80/ (2/5)=X

X=200

:iagree:

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There is no difference - he is doing exactly the same thing. Whether he calls the fraction 0.4 or 2/5 makes no difference.

He should, however, learn to properly write out his procedure, using a variable for the unknown quantity:

80 = 0.4 of X = (2/5) X

80/ (2/5)=X

X=200

Gotcha! Thank you!

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I would also make sure he knows how to divide by a decimal, since they were clearly wanting him to practice that. 0.4 was easy to convert to a fraction, but what if the problem was "80 is .12345 of what number?" Then he'd want to use the decimal (and long division by .12345 probably isn't real exciting :lol:).

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I would also make sure he knows how to divide by a decimal, since they were clearly wanting him to practice that. 0.4 was easy to convert to a fraction, but what if the problem was "80 is .12345 of what number?" Then he'd want to use the decimal (and long division by .12345 probably isn't real exciting :lol:).

Good point, I'll make sure.

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