Sarah bought a new T-shirt for $40. The sale tax is 4%. How much was the tax?
2 answers:
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Here you go! I hope I can get brainliest!
Xy=10
x+y=29
subtract x from both sides for second equation
y=-x-29
subsitute in second equaiton
x(-x-29)=10
-x^2-29x=10
add x^2+29x to both sides
x^2+29x+10=0
quadratic formula
if you have
ax^2+bx+c=0,
x=
so
x^2+29x+10=0
a=1
b=29
c=10
x=
x=
x=
x=
x=
or 
those are the 2 numbers
aprox=-28.65 and -0.349
x+y=29
subtract x from both sides for second equation
y=-x-29
subsitute in second equaiton
x(-x-29)=10
-x^2-29x=10
add x^2+29x to both sides
x^2+29x+10=0
quadratic formula
if you have
ax^2+bx+c=0,
x=
so
x^2+29x+10=0
a=1
b=29
c=10
x=
x=
x=
x=
x=
those are the 2 numbers
aprox=-28.65 and -0.349