Pls help asapp plz

In the rectangle below ac=30 units what is de

If you are trying to move an attached term across the equal sign (=), what operation would you use to move it?

Suppose that a households monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, hcf). when graphed, the function gives a line with slope of 1.65. if the monthly cost for 13 hcf is $46.10 what is the monthly cost for 19 hcf?