Why can you use addition to check your substraction

The ratio of the longer side of a rectangle to its shorter side is 4 to 3. If the shorter side of the rectangle is 21 ft, what is the length of its longer side?

A small plant is 212 inches tall. How tall will it be in 3 weeks if it grows 34 inch each week? Which method will NOT give the correct number of inches? Multiply 212*3, and then add 34. Multiply 3*34, and then add 212. Add 212+34+34+34.

A 3-digit security code can use the numbers 0-9. How many possible combinations are there if the numbers can be repeated?

A clydesdale drinks about 120 gallons of water every 4 days at this rate about how many gallons of does a clydesdale drink in 28 days

Thirteen people with different heights have a median height of 145 cm. How many people are taller than 145 cm?

Which is a better buy, 3 pounds for $8.31 or 5 pounds for $12.95?

How do I divide 29.11 by 35

If f (x) = 3x^2 + 5x find f (-2) -22 -9 2 22

What percent of 99 is 72? show work

Draw a model to show 5/2 = 5x1/2