If line rt is rotated about the origin such that its image line r't' is parallel to it, then the angle of rotation would be which of the following?
a)90 °
b)180 °
c)270 °
d)360 °

Imagine an arrow pointing directly to the east. If you rotate it 180 degrees, then it ends up pointing directly west. Both arrows will form the same straight line if you join them up together at the endpoints. This idea of rotating an arrow can also apply to rotating lines as well.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

chiken

step-by-step explanation: