Explain how you can use mental math to perform the following addition. 61,438+54,579+28,562

The table above shows approximate conversions from gallons to liters. what is the value of x?

Geometry in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.

The width of a rectangle is half as long as the length. the rectangle has an area of 18 square feet. what are the length and width of the rectangle?