Question #97873

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Answer 1 · 2017-01-29T22:19:52

$d = 6$ $d=6$

Given: $2 d - 5 = 7$ $" "2d-5=7$

Determine the value of $d$ $d$

Add $5$ $color(magenta)(5)$ to both sides. This turns the 5 on the left of the = into 0

$2 d - 5 = 7 \to 2 d - 5 + 5 = 7 + 5$ $color(green)(2d-5=7" "->" "2d-5color(magenta)(+5)=7color(magenta)(+5))$

But $- 5 + 5 = 0$ $-5+5 = 0$ giving:

$\to 2 d + 0 = 12$ $" "->" "color(green)(2d+0=12)$

Divide both sides by $2$ $color(magenta)(2)$ . This turns the 2 in $2 d$ $2d$ into 1

$\to \frac{2}{2} \times d = \frac{12}{2}$ $" "color(green)( ->" "2/(color(magenta)(2)) xx d=12/(color(magenta)(2))$

But $\frac{2}{2} = 1$ $2/2=1$ giving

$\to 1 \times d = 6$ $" "color(green)(->" "1xxd=6)$
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$d = 6$ $d=6$