An even number minus an even number

Jason can mow his parents' yard in 3 hr. His brother can mow it in 4 hr. How long would it take them, working together, to mow the yard? (Assume two mowers are available.)

Is the number 3.1x10^-5 written in scientific notation? Why or why not?

87.05 multiplied by 1.6

In a deck of 52 playing cards, there are 13 different cards in the deck that are hearts. What is the probability that if you cut the deck, you'll get a heart?

A coordless phone costs $55 plus $25 for each extra handset. what is the cost of a coordless phone and 3 extra handsets

Amy got a $1,000 loan from her bank, and she had to repay $1,550. What are the principal and interest amounts in this transaction?

What is 8/9 as a decimal rounded to nearest thousandth

What is the mean cost of replacing brake pads for four different vehicles ai at the following prices $120,$235,$98,$142

If f (x) = 1/2 [x], what is f (7.6) •3 •3.5 •3.8 •4

8 people are about to board a plane. In how many ways can this be done?