Question 681901
x is successful shots
y is missed shots
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x+y=20 : rearrange as x = 20-y
10x-15y=100
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solve for x
10(20-y)-15y = 100
200 - 10y - 15y = 100
-10y-15y = 100 - 200
-25y = -100
y = 4
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x=20-4={{{highlight_green(x=16)}}}

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