An angle turns through 40 one-degree angles. what is its angle measure?
a) 5°
b) 20°
c) 40°
d) 80°

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.

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?