Pls help
-21 ÷ b = 3, b = ? and uhm this one too
3c + 1 = 10, c = ?

Pls if a cow has a mass of 9×10^2 kilograms, and a blue whale has a mass of 1.8×10^5 kilograms, which of these statements is true?

Koji is installing a rectangular window in an office building. the window is 823 feet wide and 534 feet high. the formula for the area of a rectangle is a=bh. what is the area of the window? enter your answer as a mixed number in simplest form in the box. $$ ft2

The length of a rectangle plus its width is 24 cm. the area is 143 square cm. what are the length and width of the rectangle?