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3.5 = (D/2) + (D/40) + 2.25

User Esse
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1 Answer

7 votes

Answer:

50/21 or 2.38

Explanation:

3.5 = (D/2) + (D/40) + 2.25

Make D/2 and D/40 have a common denominator of 40.

D/2(20/20) = 20D/40

New equation:

3.5 = 20D/40 + D/40 + 2.25

Combine like terms:

3.5 = (20D/40 + D/40) + 2.25

3.5 = 21D/40 + 2.25

The first step to isolating a variable is subtracting constants from both sides:

3.5 = 21D/40 + 2.25

-2.25 -2.25

3.5 - 2.25 = 21D/40

1.25 = 21D/40

Let's get rid of 40 by multiplying both sides by 40 since the inverse operation of division is multiplication.

1.25 = 21D/40

· 40 · 40

1.25(40) = 21D

50 = 21D

Now divide both sides by 21 to isolate D since the inverse operation of multiplication is division:

50 = 21D

/21 /21

D = 50/21

If you want to keep this number in a fraction in simplest form, it already is in simplest form but if you want it in decimals, (because it doesn't divide perfectly) it would be:

D = 2.38095238095

Rounded to nearest hundredth:

D = 2.38

So, your answer is 50/21 or 2.38.

User Bejond
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