The three terms are 3d/4 and -1/2 and 7. Multiply each of these terms by 4. Why 4? This is the lowest common denominator (LCD) of the fractions. If we multiply all the terms by the LCD, then the denominators will cancel out. This will get rid of the fractions.
4 times 3d/4 = 3d
4 times -1/2 = -2
4 times 7 = 28
After multiplying each term by 4, we end up with the equation 3d - 2 = 28
Let's solve for d
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3d - 2 = 28
3d-2 + 2 = 28+2 .... add 2 to both sides
3d = 30
3d/3 = 30/3 .... divide both sides by 3
d = 10
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The final answer is d = 10