Jawabanmu

2013-12-13T22:43:24+07:00
Keliling persegi panjang 240 cm
x: panjang
y: lebar

2(x+y)=240
x+y=120
y=120-x

x/y=7/5
x/(120-x)=7/5
5x=7(120-x)
5x=840-7x
12x=840
x=70

y=120-70=50 cm


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