Why is it that mathematicians use plus and minus in sixteenth century?

How do you write an expression for the number of border tiles needed to surround a pool that has L feet long and W feet wide? The upper left region of the coordinate plane is called what? What are the prime factors of 2940? What is 18.6 rounded off to the nearest tenth? What is 507 divided by 5? How many yards is in 31 in? What is 7.8 as a percent? The unique solution to a system is where the graphs of the functions what? How do you calculate longitude of a shape? How many syllables are in dumbfounded? What do you use to measure square meters? What is wicode? What is 70 percent of 58? What are the circles in the leopards coat called? When was the digital clock first used? 5.4273 using words? True or false a shifter lock mechanism prevents shifting until the break is depressed? What is 91 rounded to the nearest hundreds? What is the solution for PC when it says updating 1 of 1 do not turn off the machine or power shutdown? What does write each number in word from?