Cross multiply...
Thus,
x(x+4)=(x+12)(x+8)
expand...
x^2+4x=x^2+8x+12x+96
Simply both sides of the equation.
x^2+4x=x^2+20x+96
simply further by adding ask like terms...
-16x=96
Solve for x by making x the subject.
therefore
x=-6.
0.17/30 = x/450 <em>Use proportion</em>
76.50 = 30x <em>Cross multiply</em>
2.55 = x <em>Divide 30 both sides</em>
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7.5 minutes call would cost 2.55
R=1 s=1 x=4 or you can basically double it and be like rs=2 x=8 i dont know your options or i could help better
12x+6y= 24
Move +6y to the other side. Sign changes from +6y to -6y
12x+6y-6y= 24-6y
12x= 24-6y
divide by 12
12x/12= 24/12-6y/12
x= 2-1/2y
Answer: Od. x=2-1/2y