Răspuns:
Notam cu
x - primul
y - al doilea
x * y = 80
[tex]\frac{60}{100}x = \frac{70}{100}y \Rightarrow\frac{x}{y} = \frac{70}{100}* \frac{100}{60} = k\Rightarrow \boxed{x =7k}\\\\\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\Rightarrow \boxed{y = 6k}\\\\7k * 6k = 80 \\\\42k^2 = 80\Righxtarrow k = \sqrt{\frac{80}{42}} \Rightarrow k = \sqrt{\frac{40}{21}} \Rightarrow k = 1,4\\\\x = 7 * 1,4 \Rightarrow x = 9,8 \Rightarrow x = \: aproximativ\: 10\\\\y = 6 * 1,4 \Rightarrow y = \: aproximativ \: 8[/tex]