Y=mx+b
y=2/5x + b
b=?

Two planes leave an airport at the same time, one flying east, the other flying west. the eastbound plane travels 20 mph slower. they are 1600 mi apart after 2 hr. find the speed of each plane.

You can ride your bike around your block 6 times and the whole neighborhood 5 times in 16 minutes. you can ride your bike around your block 3 times and the whole neighborhood 10 times in 23 minutes. how long does it take you to ride around the neighborhood?

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)