Linear equations and inequalities

9000018010

Level: 
C
The salary of Peter has been increased by \(\$2\: 400\). The salary of Jane increased by \(3\, \%\) and this increase has been bigger than the increase of the Peter's salary. In the following list identify a possible old salary of Jane.
\(\$81\: 000\)
\(\$80\: 000\)
\(\$9\: 000\)
\(\$8\: 000\)

9000018110

Level: 
C
Consider a coil composed from a ferrite core and a wire winding. The mass of the core is \(2\, \mathrm{kg}\). The material for the wire is such that the mass of the wire of the length \(30\, \mathrm{m}\) is bigger than the mass of the wire of the length \(10\, \mathrm{m}\) together with the ferrite core. In the following list identify a possible mass of one meter of the wire.
\(110\, \mathrm{g}\)
\(100\, \mathrm{g}\)
\(0.01\, \mathrm{kg}\)
\(0.09\, \mathrm{kg}\)

9000018101

Level: 
B
Solve the following inequality: \[ 7 -\left (4x - 1\right ) < 3\left (x + 4\right ) \]
\(x\in \left (-\frac{4} {7};\infty \right )\)
\(x\in \left (-\infty ; \frac{4} {7}\right )\)
\(x\in \left (\frac{4} {7};\infty \right )\)
\(x\in \left (-\infty ;-\frac{4} {7}\right )\)