Question 866
First, make an equation!!!
Let the number be x:
{{{21=((4*x)-5)*3}}} or {{{21=(5-(4*x))*3}}} (Let's slove the first one first)
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First equation:
{{{21/3=(4x-5)*3/3}}}
7 = 4x-5
7+5 = 4x-5+5
12 = 4x
[x = 3]
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Second equation:
{{{21/3 = (5-4x)*3/3}}}
7 = 5-4x
7+4x = 5
4x = -2
[x = -1/2 or -0.5]
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[x = 3 or -0.5] (ANSWER!!!!)