A manufacturer of handcrafted wine racks has determined that the cost to produce \( x \) units per month is given by \( \mathrm{C}=0.2 \mathrm{x}^{2}+10,000 \). How fast is the cost per month changing when production is changing at the rate of 13 units per month and the production level is 80 units? Costs are (Round to the nearest dollar as needed.)

Arkitek itu menggunakan skala \( 1: 25 \) untuk membina model rumah tersebut. The architect uses the scale \( 1: 25 \) to build the house model. (i) Nyatakan tinggi sebenar, dalam meter, rumah itu. State the real height, in meter, of the house.

A biologist recorded the population growth of two species of frogs in a pond area starting in 2010 . The first species started with 42 frogs and increased by 6 frogs per year. The second species started with 30 frogs and increased by 8 frogs per year. A. Write an equation modeling equal populations of the frogs \( t \) years after 2010. B. In what year were the populations of the two groups of frogs equal?

Multiply: \( \frac{3}{7} \cdot \frac{2}{5}=\square \)

3. นักศึกษาเคยใช้เทคโนโลยีสารสนเทศในการดำเนินชีวิตอย่างไรบ้างจงยกตัวอย่าง

Perform the indicated operations. Write your answers in simplified form. a. \( -\frac{3}{5}-\frac{3}{8}=\square \) b. \( -\frac{3}{5} \cdot \frac{3}{8}=\square \)