\( 41^{\circ} \) Let \( |x|=2 \) and \( |y|=4 \). Calculate \( |3 x| ;|-5 y| ;|-3 x y| ;\left|\frac{5 x}{2 y}\right| \). \( 2^{\circ} \) What is the sign of the following, knowing that \( z \) is a strictly positive number ? \( |z| ;|-z| ;-|-z| ; z|z| ;(-z) \times|-z| \)

In a stack of red and blue T-shirts, blue T-shirts and red T-shirts are in the ratio \( 4: 3 \). If then are 49 T-shirts, find the ratio of blue \( T \)-shirts to the total number of T-shirts-

The value of a car decreases exponentially over time. If the initial value is $20,000 and it depreciates by 15% each year, what will be its value after 2 years?

1. Choose the correct answer from the given ones : \( \begin{array}{llll}\text { 1 If } X=\{2\}, Y=\{3,4\} \text {, then } n\left(X^{2}\right) \times \mathrm{n}(\mathrm{Y})=\ldots \ldots \ldots \ldots \\ \begin{array}{llll}\text { (a) } 1 & \text { (b) } 2 & \text { (c) } 3 & \text { (d) } 4\end{array}\end{array} \).

La cantidad de un material radiactivo disminuye a la mitad cada 10 años. Si comenzamos con 80 gramos, ¿cuánto quedará después de 30 años?

3 The middle proportional between the two numbers 3 and 12 is ............. \( \begin{array}{llll}\text { (a) } \pm 3 & \text { (b) } \pm 4 & \text { (c) } \pm 6 & \text { (d) } \pm 12\end{array} \)