12D
Số kg protein là: \(\dfrac{100.34}{1000}=1,02\left(kg\right)\)
13B
Số ngày là: \(168.\dfrac{35}{28}=210\left(ngày\right)\)
14C
\(x=\left(\dfrac{10}{24}.36\right):\left(-3\right)=-5\)
16C
\(\dfrac{x}{y}=\dfrac{2}{6}=\dfrac{1}{3}\Rightarrow y=3x\)
\(y-x=3x-x=2x=-20\Rightarrow x=-10\Rightarrow y=-30\)
\(\Rightarrow x.y=\left(-10\right).\left(-30\right)=300\)
17A
\(x,y\) tỉ lệ thuận: \(\dfrac{y_1}{y_2}=\dfrac{x_1}{x_2}\Rightarrow x_2=x_1:\dfrac{y_1}{y_2}=10:\dfrac{16}{8}=5\)
18D
Có: \(MN+MP>NP>MN-MP\Rightarrow6>NP>4\)
19B
20B