a+b+c+d=180
a=d/4-->b/2=d/4-->d=2b
c=a-20-->c=b/2-20
2a=b-->a=b/2
b/2+b+b/2+2b=200
4b=200
b=50
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Source: Beat The GMAT — Problem Solving |
IMO E (50)
You can express the equation a+b+c+d=180 in terms of a only.
a+4a+a-20+2a=180
8a-20=180
8a=200
a=25
b=2a=2*25=50
You can express the equation a+b+c+d=180 in terms of a only.
a+4a+a-20+2a=180
8a-20=180
8a=200
a=25
b=2a=2*25=50
a = (d/4)
c = a - 20
and 2a = b
a + b +c + d = 180
Now just replace b, c, d in terms of a and solve.
c = a - 20
and 2a = b
a + b +c + d = 180
Now just replace b, c, d in terms of a and solve.
Nice job guys! The official answer is E.
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